Semiconductor devices including bit line contact plug and peripheral transistor

ABSTRACT

A semiconductor device having a cell area and a peripheral area includes a semiconductor substrate, a cell insulating isolation region delimiting a cell active region of the semiconductor substrate in the cell area, a word line disposed within the semiconductor substrate in the cell area, a bit line contact plug disposed on the cell active region, a bit line disposed on the bit line contact plug, a peripheral insulating isolation region delimiting a peripheral active region of the semiconductor substrate in the peripheral area, and a peripheral transistor including a peripheral transistor lower electrode and a peripheral transistor upper electrode. The bit line contact plug is formed at the same level in the semiconductor device as the peripheral transistor lower electrode, and the bit line electrode is formed at the same level in the semiconductor device as the peripheral transistor upper electrode.

PRIORITY STATEMENT

This application is a Continuation of application Ser. No. 14/527,450, filed Oct. 29, 2014, which is a Continuation of application Ser. No. 13/864,347, filed Apr. 17, 2013, now U.S. Pat. No. 8,901,645, issued Dec. 2, 2014, which is a Continuation of application Ser. No. 13/072,907, filed Mar. 28, 2011, now U.S. Pat. No. 8,461,687, issued Jun. 11, 2013, which claims the benefits of priorities under 35 U.S.C. §119 from Korean Patent Applications Nos. 10-2010-0031560, 10-2010-0031562, and 10-2010-31564 filed on Apr. 6, 2010.

BACKGROUND

The inventive concepts relate to semiconductor devices having bit line contact plugs and buried channel array transistors, methods of fabricating the semiconductor devices, and to a semiconductor module, an electronic circuit board, and an electronic system including such semiconductor devices.

As semiconductor devices become more highly integrated, the architecture of semiconductor devices and processes of fabricating semiconductor devices are gradually becoming more elaborate and complicated. To meet the demand for highly integrated semiconductor devices, a buried word line structure, a buried channel array transistor, and 6F2 layout architecture have been suggested.

SUMMARY

According to the inventive concepts, there is provided an embodiment of a semiconductor device including a semiconductor substrate, a cell insulating isolation region, a word line, a bit line contact plug, a bit line, a peripheral insulating isolation region, and a peripheral transistor having electrodes disposed at the same levels in the semiconductor device as the bit line contact plug and electrode of the bit line, respectively. The cell insulating isolation region is disposed within the semiconductor substrate in a cell area of the semiconductor device, and delimits a cell active region of the semiconductor substrate in the cell area. The word line extends in the semiconductor substrate in the cell area of the semiconductor device. The bit line contact plug is disposed on the cell active region. The bit line is disposed on the bit line contact plug and comprises a bit line electrode. The peripheral insulating isolation region is disposed within the semiconductor substrate in a peripheral area of the semiconductor device, and delimits a peripheral active region of the semiconductor substrate in the peripheral area. The peripheral transistor has a lower electrode disposed on the peripheral active region of the semiconductor substrate and an upper electrode disposed on the lower electrode. The bit line contact plug occupies the same level in the semiconductor device as the lower electrode of the peripheral transistor. The bit line electrode occupies the same level in the semiconductor device as the upper electrode of the peripheral transistor.

According to the inventive concepts, there is provided a semiconductor module having a plurality of semiconductor devices at least one of which is a semiconductor device having the features described above, a module board to which the semiconductor devices are mounted, and module contact terminals disposed in parallel along one edge of the module board. The module contact terminals are electrically connected to the semiconductor devices, respectively.

According to the inventive concepts, there is provided an electronic system having a control unit, an input unit, an output unit, a storage unit, and a communication unit, wherein at least one of the units includes a semiconductor device having the features described above.

According to the inventive concepts, there is provided an embodiment of a semiconductor device including a cell insulating isolation region, a plurality of word lines, bit line contact plugs, first and second bit lines, a peripheral insulating isolation region, surface insulating layer, a peripheral transistor whose electrodes are disposed at the same levels in the semiconductor device as the bit line contact plugs and the electrodes of the bit lines, respectively. The cell insulating isolation region is provided within the semiconductor substrate in a cell area of the semiconductor device, and delimits cell active regions of the semiconductor substrate in the cell area. Thus, the cell insulating isolation region electrically isolates the cell active regions from one another. The word lines each extend in the semiconductor substrate in the cell area of the semiconductor device. The bit line contact plugs are disposed on the cell active regions, respectively. The bit lines each extend longitudinally on the semiconductor substrate in a first direction, with the first and second bit lines alternately disposed in a second direction perpendicular to the first direction. The peripheral insulating isolation region extends within the semiconductor substrate in a peripheral area of the semiconductor device, and delimits a peripheral active region of the semiconductor substrate in the peripheral area. The surface insulating layer may be disposed over the semiconductor substrate and interposed between a first segment of the first bit line and the cell active region on which said one of the bit line contact plugs is disposed and between a second segment of the second bit line and the cell insulating isolation region The peripheral transistor has a lower electrode disposed on the peripheral active region of the semiconductor substrate, and an upper electrode disposed on the lower electrode. The first segment of the first bit line is vertically aligned with and disposed on one of the bit line contact plugs, and the corresponding the second segment of the second bit line closest to the first bit line in the second direction is vertically aligned with and disposed on the cell insulating isolation region. The bit line contact plug occupies the same level in the semiconductor device as the lower electrode of the peripheral transistor, and the bit line electrodes of the first and second bit lines occupy the same level in the semiconductor device as the upper electrode of the peripheral transistor.

According to the inventive concepts, there is provided an embodiment of a method of fabricating a semiconductor device in which a bit line contact plug and bit line electrode are formed at the same level in the semiconductor device as electrodes of a peripheral transistor, respectively. A cell insulating isolation is formed in a first portion of a semiconductor substrate constituting a cell area of the semiconductor device so as to delimit a cell active region. A word line is formed in the first portion of the semiconductor substrate constituting the cell area. The bit line contact plug is formed on the cell active region. A bit line is formed on the bit line contact plug. A peripheral insulating isolation region is formed in a second portion of the semiconductor substrate constituting a peripheral area of the semiconductor device so as to delimit a peripheral active region. A peripheral transistor, comprising the peripheral transistor lower electrode and peripheral transistor upper electrode, is formed on the second portion of the semiconductor substrate constituting the peripheral area. The bit line contact plug and the lower electrode of the peripheral transistor are formed at the same level in the semiconductor device. The bit line electrode and the upper electrode of the peripheral transistor are also formed at the same level in the semiconductor device.

According to the inventive concepts, there is provided an embodiment of a method of fabricating a semiconductor device in which, through the use of a patterning process, a lower electrode of a peripheral transistor is formed at the same level in the semiconductor device as a bit line contact plug. A word line is formed in a first portion of a semiconductor substrate constituting a cell area of the semiconductor device. A first insulating layer is formed over the first portion of the semiconductor substrate corresponding to the cell area of the semiconductor device and over a second portion of the semiconductor substrate corresponding to the peripheral area of the semiconductor device. The first insulating layer is formed to be thicker on the first portion of the semiconductor substrate constituting the cell area than on the second portion of the semiconductor substrate constituting the peripheral area. A first electrode layer is formed on the first insulating layer in the peripheral area. A bit line contact plug is formed to extend through the first insulating layer in the cell area, and so as to be electrically conductively connected to the semiconductor substrate. A barrier layer is formed over the first insulating layer, the bit line contact plug, and the first electrode layer. A second electrode layer is formed over the barrier layer. A bit line is formed in the cell area and a peripheral transistor is formed in the peripheral area, including by patterning the second electrode layer and the barrier layer.

According to the inventive concepts, there is provided an embodiment of a method of fabricating a semiconductor device in which an electrode of a peripheral transistor is formed at the same level in the semiconductor device as a bit line contact plug, and a bit line and an upper portion of a peripheral transistor are formed by common processing of a semiconductor substrate. A trench is formed in a first portion of the semiconductor substrate constituting a cell area and in a second portion of the semiconductor substrate constituting a peripheral area of the semiconductor device. Then the trench in the cell area and in the peripheral area is filled with insulating material, to thereby form a trench type of cell insulating isolation region delimiting a cell active region in the cell area, and a trench type of peripheral insulating isolation region delimiting a peripheral active region in the peripheral area. A buried word line that crosses the cell active region and the cell insulating isolation region is formed. Peripheral transistor insulation is formed on the semiconductor substrate in the peripheral area, and surface insulating layer covering sidewalls of the bit line contact plug is formed on the semiconductor substrate in the cell area. A lower electrode of a peripheral transistor is formed on the peripheral transistor insulating layer, and the bit line contact plug is formed on the cell active region, by processes wherein the lower electrode and the bit line contact plug are completed at the same time and are formed at the same level in the semiconductor device. A surface insulating layer covering sidewalls of the bit line contact plug and the peripheral transistor lower electrode are formed. Then, a bit line is formed on the bit line contact plug, and simultaneously an upper portion of the peripheral transistor is formed on the peripheral transistor lower electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concepts will be better understood from the following detailed description of embodiments thereof made below with reference to the accompanying drawings. It should be understood that the drawings may exaggerate various aspects of the embodiments for clarity.

FIG. 1A is a schematic diagram of the layout of embodiments of semiconductor devices in accordance with the inventive concepts;

FIG. 1B is a sectional view of an embodiment of a semiconductor device in accordance with the inventive concepts;

FIGS. 2A to 2F are each a sectional view of a respective embodiment of semiconductor device, in accordance with the inventive concepts, with regions (a), (b), (c) and (d) in each of the figures being regions along lines A-A′, B-B′, C-C′ and D-D′ of FIG. 1A, respectively;

FIGS. 3A to 3C are each a longitudinal sectional view taken along line C-C′ in FIG. 1A, and each illustrating a region of a respective embodiment of a semiconductor device where several bit line contact plugs are provided, in accordance with the inventive concepts;

FIGS. 4A to 4L are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 5A to 5G are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 6A to 6I are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 7A to 7E are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 8A to 8B are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 9A to 9E are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 10A to 10I are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 11A to 11J are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 12A to 12G are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 13A to 13F are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 14A to 14D are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 15A to 15J are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 16A to 16F are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 17A to 17F are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 18A to 18J are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 19A to 19H are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 20A 20K are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 21A 21K are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 22A 22K are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 23A 23K are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIGS. 24A 24I are each a sectional view and together illustrate an embodiment of a method of fabricating a semiconductor device in accordance with the inventive concepts, wherein regions (a), (b), (c) and (d) in each of the figures are regions along lines A-A′, B-B′, C-C′, and D-D′ in FIG. 1A, respectively;

FIG. 25A is a schematic diagram of an example a semiconductor module including a semiconductor device in accordance with the inventive concepts;

FIG. 25B is a block diagram of an example of an electronic circuit board including a semiconductor device in accordance the inventive concepts; and

FIG. 25C a block diagram of an example of an electronic system including a semiconductor device in accordance with the inventive concepts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments and examples of embodiments of the inventive concept will be described more fully hereinafter with reference to the accompanying drawings. In the drawings, the sizes and relative sizes and shapes of elements, layers and regions, such as implanted regions, shown in section may be exaggerated for clarity. In particular, the cross-sectional illustrations of the semiconductor devices and intermediate structures fabricated during the course of their manufacture are schematic. Also, when like numerals appear in the drawings, such numerals are used to designate like elements.

Furthermore, spatially relative terms, such as “upper,” and “lower” are used to describe an element's and/or feature's relationship to another element(s) and/or feature(s) as illustrated in the figures. Thus, the spatially relative terms may apply to orientations in use which differ from the orientation depicted in the figures. Obviously, though, all such spatially relative terms refer to the orientation shown in the drawings for ease of description and are not necessarily limiting as embodiments according to the inventive concept can assume orientations different than those illustrated in the drawings when in use.

It will also be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer or intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on” or “directly connected to” another element or layer, there are no intervening elements or layers present. The same holds true for an element or layer described as being interposed “between” two features.

It will be understood that although the terms first, second, third etc. are used herein to describe various elements, regions, layers, etc., these elements, regions, and/or layers are not limited by these terms. These terms are only used to distinguish one element, layer or region from another.

Furthermore, spatially relative terms, such as “upper,” and “lower” are used to describe an element's and/or feature's relationship to another element(s) and/or feature(s) as illustrated in the figures. Thus, the spatially relative terms may apply to orientations in use which differ from the orientation depicted in the figures. Obviously, though, all such spatially relative terms refer to the orientation shown in the drawings for ease of description and are not necessarily limiting as embodiments according to the inventive concept can assume orientations different than those illustrated in the drawings when in use. In addition, the term “surface” as used alone or as preceded by “upper”, “top” or “bottom” generally refers to a surface of a layer or feature that is the uppermost or bottommost surface of that layer or feature in the orientation depicted, as would be clear from the drawings and context of the written description. The term “similar” is used to mean the same or substantially same. Also, the term “the same level” (in the semiconductor device) will be readily understood by those skilled in the art of semiconductor device architecture, as mainly referring to “coplanar” when used to described surfaces or as mainly referring to “occupying the same layer” when used to described features. With respect to the latter, two features described as being disposed at or occupying “the same level” in the semiconductor device may mean that the upper surfaces of the features are substantially coplanar and that the lower surfaces of the features are also substantially coplanar, although slight deviations are possible and still allow for the features to be considered as occupying the same level in the semiconductor device.

An example of a layout of semiconductor devices in accordance with the inventive concepts will now be described with reference to FIG. 1A and FIG. 1B.

Referring first to FIG. 1A, semiconductor devices according to the inventive concepts have a cell area CA and peripheral area PA. The cell area CA may include a cell insulating isolation region 2 c (or regions such as when considered in section as shown in the drawing), cell active regions 3 c, and word lines 4 in a semiconductor substrate 1. The cell area CA may further include bit lines 7 and bit line contact plugs 6 above/on the semiconductor substrate 1. The peripheral area PA includes a peripheral insulating isolation region 2 p and a peripheral active region 3 p in the semiconductor substrate 1. The peripheral area PA also includes a peripheral transistor 8 above/on the semiconductor substrate 1.

The cell area CA may include a plurality of regularly arranged cell transistors and/or a plurality of cell capacitors. The peripheral area PA may include a plurality of peripheral transistors such as CMOS transistors which may compose logic circuits. The cell active regions 3 c may be bar-shaped, i.e., may be elongate. Both of the word lines 4 and the bit lines 7 may obliquely cross the cell active regions 3 c.

The cell active regions 3 c may be conductive regions formed by injecting impurity ions into the semiconductor substrate 1. For example, exposed regions between the word lines 4 may be source regions or drain regions.

The cell insulating isolation regions 2 c may be shallow trench isolation (STI) may regions formed between the cell active regions 3 c.

The word lines 4 may be of a buried type meaning that the word lines 4 are buried in the semiconductor substrate 1. Accordingly, the word lines 4 may cross the cell active regions 3 c and the cell insulating isolation regions 2 c. Furthermore, the word lines 4 may be formed in portions of the cell active regions 3 c and the cell insulating isolation regions 2 c.

The bit lines 7 may cross the word lines 4 at right angles. The bit lines 7 may be formed above the semiconductor substrate 1. The bit lines 7 may each be electrically and/or physically connected to several of the cell active regions 3 c through a plurality of the bit line contact plugs 6, respectively. To this end, the bit line contact plugs 6 may be vertically aligned with central portions of the cell active regions 3 c. The layout of the peripheral region PA is shown simplified for the sake of brevity.

Referring to FIG. 1B, the bit line 7 may include bit line conductive layers 7 a, 7 b and 7 c at a lower part, a bit line metal layer 7 d at a middle part, a bit line capping layer 7 e at an upper part, bit line side wrapping layers 7 f at side parts and a bit line upper wrapping layer 7 g at an uppermost part.

The peripheral transistor 8 may include a peripheral transistor insulating layer 8 a, a peripheral transistor lower electrode 8 b, peripheral transistor conductive layers 8 c, 8 d, and 8 e, a peripheral transistor upper electrode 8 f, a peripheral transistor capping layer 8 g, peripheral transistor side wrapping layers 8 h, and a peripheral transistor upper wrapping layer 8 i. As shown in FIG. 1B, the semiconductor device may further include interlayer dielectric layers 9 c and 9 p, storage node contact plugs 10 c, and storage nodes 10 n, which are omitted in FIG. 1A.

The bit line conductive layers 7 a, 7 b and 7 c may be spaced apart from a surface of the semiconductor substrate 1 with a height of the surface insulating layer 5 and/or the bit line contact plug 6.

Portions of the bit line side wrapping layers 7 f adjacent to the surface of the semiconductor substrate 1 may be removed.

Accordingly, contacting areas between the storage node contact plugs 10 c and the cell active region 3 of the semiconductor substrate 1 may be expanded. The bit line contact plug 6 may extend into the semiconductor substrate 1. In other words, the bottom of the bit line contact plug 6 may be situated lower than the surface of the semiconductor substrate 1.

The bit line contact plug 6 may be partially or completely surrounded by surface insulating layer 5. The surface insulating layer 5 may comprise silicon oxide, silicon nitride or silicon oxynitride. The surface insulating layer 5 may be formed between the semiconductor substrate 1 and the bit line 7. That is, the semiconductor substrate 1 and the bit line 7 may be spaced apart from each other by the surface insulating layer 5. These elements will be described in more detail later.

Other examples of the embodiment of a semiconductor device according to the inventive concepts will be described in FIGS. 2A to 2F. In these figures, region (d) also includes a core area of the semiconductor device. The core area, at the left side of region (d), is an area surrounding the cell area CA and is located between the cell area CA and peripheral area PA. Although the core area and the peripheral area PA may be significantly spaced apart from each other, the areas are shown adjacent to each other for ease of illustration and description. The core area may have various shapes all within the scope of the inventive concepts.

Referring to FIG. 2A, this example of a semiconductor device in accordance with the inventive concepts includes cell insulating isolation regions 12 c, cell active regions 13 c, and word lines 14 all formed in a semiconductor substrate 11, and a bit line 17, a bit line contact plug 16 and a surface insulating layer 15 all formed above/on the semiconductor substrate 11, in a cell area CA. The semiconductor device also includes peripheral insulating isolation regions 12 p and a peripheral active region 13 p formed in the semiconductor substrate 11, and a peripheral transistor 18 formed on the semiconductor substrate 11, in a peripheral area PA.

The cell insulating isolation regions 12 c and the peripheral insulating isolation region 12 p may be STI regions, and sizes of the cell insulating isolation regions 12 c may be variously established according to characteristics of the semiconductor device.

The cell active regions 13 c and the peripheral active region 13 p may be portions of the semiconductor substrate 11, and may include well regions injected with impurities.

The word lines 14 may each include a word line insulating layer 14 a, a word line capping layer 14 b, and a word line electrode 14 c. The word line insulating layer 14 a may comprise an oxide material such as silicon oxide, hafnium oxide or another oxide material. The word line capping layer 14 b may comprise an insulating material such as silicon oxide, silicon nitride or silicon oxynitride. The word line electrode 14 c may comprise doped silicon, metals, metal silicides, or metal compounds. The elements 14 a, 14 b, and 14 c of the word lines 14 are illustrated as simply shaped so that the inventive concepts may be easily understood but may have various other shapes.

The bit line contact plug 16 may be formed in a pillar shape or a mesa shape. The bit line contact plug 16 may electrically and/or physically connect the cell active region 13 c to the bit line 17. The bit line contact plug 16 may comprise doped silicon, metals, metal silicides, or metal compounds. The bit line contact plug 16 may be formed to a first width in the word line 14 extending direction and a second width in the bit line 17 extending direction. The first width and the second width may be different from each other. For example, the first width may be smaller than the second width. That is, the bit line contact plug 16 may have the shape of a circle, an oval or a rectangle in plan.

The bit line contact plug 16 may be partially or completely surrounded by the surface insulating layer 15. The surface insulating layer 15 may comprise silicon oxide, silicon nitride or silicon oxynitride. The surface insulating layer 15 may be formed between the semiconductor substrate 11 and the bit line 17. That is, the semiconductor substrate 11 and the bit line 17 may be spaced apart from each other by the surface insulating layer 15.

The bit line 17 may include a lower bit line metal silicide layer 17 a, a bit line barrier layer 17 b, an upper bit line metal silicide layer 17 c, a bit line electrode 17 d, and a bit line capping layer 17 e. When the bit line contact plug 16 is of doped silicon and the bit line electrode 17 d includes a metal, the lower bit line metal silicide layer 17 a may be of a metal to form a metal silicide layer or a metal silicide. The lower bit line metal silicide layer 17 a may be a metal layer at portions not in contact with the bit line contact plug 16. Accordingly, the lower bit line metal silicide layer 17 a may be a material layer including both a metal silicide and a metal. The bit line barrier layer 17 b may comprise titanium nitride (TiN). The upper bit line metal silicide layer 17 c may comprise a metal silicide or a metal nitride. The bit line electrode 17 d may include the same metal as the upper bit line metal silicide layer 17 c. For example, when the upper bit line metal silicide layer 17 c includes tungsten (W), the bit line electrode 17 d may also include tungsten (W). The bit line capping layer 17 e may be of an insulating material such as silicon nitride or silicon oxynitride.

The bit line 17 may be surrounded by the bit line wrapping layer 19 c. The bit line wrapping layer 19 c may include a bit line upper wrapping layer 19 ca and a bit line side wrapping layer 19 cb. The bit line side wrapping layer 19 cb may be formed into spacer shapes. In the spacer shapes, it may be understood that the lowermost width is larger than the uppermost width of the bit line side wrapping layer 19 cb. The bit line wrapping layer 19 c may comprise silicon oxide, silicon nitride, or silicon oxynitride. The bit line wrapping layer 19 c may also be formed on sidewalls of the surface insulating layer 15.

The peripheral transistor 18 may include a peripheral transistor insulating layer 18 a, a peripheral transistor lower electrode 18 b, a peripheral transistor lower metal silicide layer 18 c, a peripheral transistor barrier layer 18 d, a peripheral transistor upper metal silicide layer 18 e, a peripheral transistor upper electrode 18 f, and a peripheral transistor capping layer 18 g.

The peripheral transistor insulating layer 18 a may be of the same material as the surface insulating layer 15. The peripheral transistor lower electrode 18 b may comprise doped silicon. The peripheral transistor lower electrode 18 b may be formed to occupy the same or similar level as the bit line contact plug 16. The peripheral transistor lower metal silicide layer 18 c, the peripheral transistor barrier layer 18 d, and the peripheral transistor upper metal silicide layer 18 e may be of the same materials and/or may have the same widths as the lower bit line metal silicide layer 17 a, the bit line barrier layer 17 b, and the upper bit line metal silicide layer 17 c, respectively. The peripheral transistor upper electrode 18 f may be of the same material and/or may have the same width as the bit line electrode 17 d. The peripheral transistor capping layer 18 g may be of the same material and/or may have the same width as the bit line capping layer 17 e.

The peripheral transistor 18 may be surrounded by a peripheral transistor wrapping layer 19 p. The peripheral transistor wrapping layer 19 p may include a peripheral transistor upper wrapping layer 19 pa and a peripheral transistor side wrapping layer 19 pb. The peripheral transistor side wrapping layer 19 pb may also be formed in the spacer shape. The peripheral transistor wrapping layer 19 p may be of the same material and/or may have the same or similar structure as the bit line wrapping layer 19 c. A similar structure may include a similar thickness or a thickness difference of less than dozens of A. For example, the thickness difference of the structures is less than 100 Å in an example of this embodiment. The thickness difference may be over 100 Å due to process

conditions imposing a heavy burden from a loading effect. Accordingly, the numerical limitations are not absolute. The elements of the similar structures may be formed by the same processes during the fabricating of the semiconductor device. Furthermore, it will be understood that similar thicknesses refer to thicknesses that differ only within a range of errors due basically only to process variables. The error ranges may be numerical ranges in consideration of process variations, loading effects, and/or local peculiarities. Conventionally, acceptable error ranges are within ±10% of target values.

In an example of this embodiment, the top surface of the bit line contact plug 16 may be formed to a higher level than the top surface of the surface insulating layer 15. In other words, the bit line contact plug 16 may protrude from the top surface of the surface insulating layer 15.

Referring to FIG. 2B, this embodiment of a semiconductor device in accordance with the inventive concepts includes cell insulating isolation regions 22 c, cell active regions 23 c, and word lines 24 all formed in a semiconductor substrate 21, and a bit line 27, a bit line contact plug 26 and a surface insulating layer 25 all formed above/on the semiconductor substrate 21, in a cell area CA. The semiconductor device also includes peripheral insulating isolation regions 22 p and a peripheral active region 23 p all formed in the semiconductor substrate 21, and a peripheral transistor 28 formed on the semiconductor substrate 21, in a peripheral area PA.

The elements shown in FIG. 2B can be understood by referring to the elements having similar reference numerals shown in FIG. 2A. In the example embodiment, the surface insulating layer 25 may be formed as lamina or multi layers. For example, the surface insulating layer 25 may include a lower surface insulating layer 25 l and an upper surface insulating layer 25 u. The lower surface insulating layer 25 l and the upper surface insulating layer 25 u may be of materials having a different etch selectivity from each other, e.g., silicon oxide and silicon nitride. An example of this embodiment in which both the lower surface insulating layer 25 l and the upper surface insulating layer 25 u are silicon oxide will be described in more detail later. Top surfaces of the bit line contact plug 26 and the surface insulating layer 25 may be disposed at a similar level. That is, the bit line contact plug 26 and the surface insulating layer 25 may be formed simultaneously, e.g., using the same etching step and/or CMP process.

Referring to FIG. 2C, this embodiment of a semiconductor device in accordance with the inventive concepts includes cell insulating isolation regions 32 c, cell active regions 33 c, and word lines 34 all formed in a semiconductor substrate 31, and a bit line 37, a bit line contact plug 36 and a surface insulating layer 35 all formed above/on the semiconductor substrate 31, in a cell area CA. The semiconductor device also includes peripheral insulating isolation regions 32 p and a peripheral active region 33 p formed in the semiconductor substrate 31, and a peripheral transistor 38 formed on the semiconductor substrate 31, in a peripheral area PA.

The elements shown in FIG. 2C can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A and 2B. The surface insulating layer 35 may also be constituted by lamina or multi layers. That is, the surface insulating layer 35 may include a lower surface insulating layer 35 l and an upper surface insulating layer 35 u. A surface of the bit line contact plug 36 may be at a lower level than the surface of the surface insulating layer 35. The bit line contact plug 36 may be formed by using an etching process having an etching selectivity with the surface insulating layer 35 or a CMP process.

Referring to FIG. 2D, this embodiment of a semiconductor device in accordance with the inventive concepts includes cell insulating isolation regions 42 c, cell active regions 43 c, and word lines 44 all formed in a semiconductor substrate 41, and a bit line 47, a bit line contact plug 46 and a surface insulating layer 45 all formed above/on the semiconductor substrate 41, in a cell area CA. The semiconductor device also includes peripheral insulating isolation regions 42 p and a peripheral active region 43 p formed in the semiconductor substrate 41, and a peripheral transistor 48 formed on the semiconductor substrate 41, in a peripheral area PA.

The elements shown in FIG. 2D can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2C. The cell surface insulating layer 45 c may also be constituted by lamina or multi layers. That is, the cell surface insulating layer 45 c may include a lower cell surface insulating layer 45 c 1 and an upper cell surface insulating layer 45 cu. The lower cell surface insulating layer 45 c 1 may be formed on a surface of the semiconductor substrate 41 and sidewalls of the bit line plug 46. The surface of the bit line contact plug 46 and the surface of the cell surface insulating layer 45 c may be situated at similar levels. The bit line wrapping layer 49 c may be formed on the cell surface insulating layer 45 c. The cell surface insulating layer 45 c may extend onto the peripheral area PA and be formed into a peripheral surface insulating layer 45 p. The peripheral surface insulating layer 45 p may include a lower surface insulating layer 45 p 1 and an upper peripheral surface insulating layer 45 pu. A peripheral transistor wrapping layer 49 p may be formed on the peripheral surface insulating layer 45 p. The lower peripheral surface insulating layer 45 p 1 may be formed on a peripheral transistor insulating layer 48 a and/or sidewalls of the peripheral transistor lower electrode 48 b.

Referring to FIG. 2E, this embodiment of a semiconductor device in accordance with the inventive concepts includes cell insulating isolation regions 52 c, cell active regions 53 c, and word lines 54 all formed in a semiconductor substrate 51, and a bit line 57 and a bit line contact plug 56 p formed above/on the semiconductor substrate 51, in a cell area CA. The semiconductor device also includes peripheral insulating isolation regions 52 p and a peripheral active region 53 p formed in the semiconductor substrate 51, and a peripheral transistor 58 formed on the semiconductor substrate 51, in a peripheral area PA.

The elements shown in FIG. 2E can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2D. A cell surface insulating layer 55 c may be formed on the cell area CA and a peripheral surface insulating layer 55 p may be formed on the peripheral area PA. The cell surface insulating layer 55 c and the peripheral surface insulating layer 55 p may have different thicknesses from each other. A line type contact pad 56 l may be formed between the bit line 57 and the bit line contact plug 56 p. The line type contact pad 56 l may be of the same material as the bit line contact plug 56 p. For example, the line type contact pad 56 l may comprise silicon or a silicide. The line type contact pad 56 l may have the same shape as the bit line 57 in plan.

Referring to FIG. 2F, this embodiment of a semiconductor device in accordance with the inventive concept includes cell insulating isolation regions 62 c, cell active regions 63 c and word lines 64 all formed in a semiconductor substrate 61, and a bit line 67, a bit line contact plug 66 p and a surface insulating layer 65 all formed above/on the semiconductor substrate 61, in the cell area CA. The semiconductor device also includes peripheral insulating isolation regions 62 p and a peripheral active region 63 p formed in the semiconductor substrate 61, and a peripheral transistor 68 formed on the semiconductor surface 61, in the peripheral area PA.

The elements shown in FIG. 2F can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2E. A line type contact pad 66 l may be formed between the bit line 67 and the bit line contact plug 66 p. The line type contact pad 66 l may be of the same material as the bit line contact plug 66 p. The line type contact pad 66 l may comprise silicon or a silicide. The line type contact pad 66 l may have the same shape as the bit line 67 in plan.

As shown in FIGS. 2A to 2F, the bit line contact plugs 16, 26, 36, 46, 56 p, and 66 p may protrude only from or may be recessed in the bottom of the bit lines 17, 27, 37, 47, 57, and 67. For example, the bit line contact plugs 16, 26, 36, 46, 56 p, and 66 p may protrude only or may be recessed in the lower bit line metal silicide layers 17 a, 27 a, 37 a, 47 a, 57 a, and 67 a. Either of these characteristics can be employed in the various examples of embodiments described herein.

FIGS. 3A to 3C each illustrate a region of a respective embodiment of a semiconductor device, in accordance with the inventive concepts, where several of the bit line contact plugs are provided.

Referring to FIG. 3A, this embodiment of a semiconductor device includes insulating isolation regions 72 and active regions 73 in a semiconductor substrate 71, and bit line contact plugs 76 and bit lines 77 above/on the semiconductor substrate 71. The elements shown in FIG. 3A can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2F. The bit lines 77 may each include a lower bit line metal silicide layer 77 a, a bit line barrier layer 77 b, an upper bit line metal silicide layer 77 c, and a bit line electrode 77 d.

Some of the bit lines 77 are aligned with the contact plugs 76, respectively, whereas others of the bit lines 77 are not aligned with a contact plug 76. The bit lines 77 aligned with the contact plugs 76 have a first width W1 and the bit lines 77 not aligned with a contact plug 76 have a second width W2. The first width W1 is greater than the second width W2. That is, according to the inventive concepts, the bit lines 77 aligned with the bit line contact plugs 76 have expanded widths. FIG. 3A shows bit line contact plugs 76 each having the same structure as the bit line contact plug 16 shown in FIG. 2A. However, as will be clear from the description below, this aspect of the inventive concept can be applied to bit line contact plugs having the structures shown in FIGS. 2B to 2F.

Referring to FIG. 3B, for example, this embodiment of a semiconductor device in accordance with the inventive concept includes insulating isolation regions 82 and active regions 83 in a semiconductor substrate 81, and bit line contact plugs 86 and bit lines 87 above/on the semiconductor substrate 81. The elements shown in FIG. 3B can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2F.

In this embodiment, each bit line 87 aligned with a bit line contact plugs 86 has a width W3 greater than the width W4 of each bit line 87 that is not aligned with a bit line contact plug. That is, again, according to the inventive concepts, the bit lines 87 aligned with the bit line contact plugs 86 have expanded widths. FIG. 3B shows bit line contact plugs 86 each having the same structure as the contact plug 26 shown in FIG. 2B.

And referring to FIG. 3C, for example, this embodiment of a semiconductor device in accordance with the inventive concepts includes insulating isolation regions 92 and active regions 93 in a semiconductor substrate 91, and bit line contact plugs 96 and bit lines 97 above/on the semiconductor substrate 91. The elements shown in FIG. 3C can be understood by referring to the elements having similar reference numerals shown in FIGS. 2A to 2F.

In this embodiment, each bit line 97 aligned with bit line contact plugs 96 has a width W5 greater than the width W6 of each bit line 97 that is not aligned with a bit line contact plug 96. That is, again, according to the inventive concepts, the bit lines 97 that are aligned with the bit line contact plugs 96 have expanded widths. FIG. 3C shows bit line contact plugs 96 each having the same structure as the bit line contact plug 36 shown in FIG. 2C.

Embodiments of methods of fabricating semiconductor devices in accordance with the inventive concepts will now be described with reference to FIGS. 4A-L, 5A-G, . . . 24A-I. In these figures, as is clear from the description of the drawings above, regions (a), (b), and (c) are regions, respectively, of the cell area CA of the semiconductor device. Furthermore, the left side of region (d) is a region of the core area and the right side of region (d) is a region of the peripheral area of the semiconductor device.

Embodiment 1

Referring to FIG. 4A, cell insulating isolation regions 102 c defining cell active regions 103 c, and word lines 104 may be formed in a portion of a semiconductor substrate 101 corresponding to a cell area CA of the final semiconductor device, and peripheral insulating isolation regions 102 p defining peripheral active regions 103 p may be formed in a portion of the semiconductor substrate 101 corresponding to a peripheral area PA of the final semiconductor device. The cell insulating isolation regions 102 c, the peripheral insulating isolation regions 102 p, and the word lines 104 may be understood by referring to FIG. 2A. The semiconductor substrate 101, the surfaces of the cell insulating isolation regions 102 c, the peripheral insulating isolation regions 102 p, and the word lines 104 do not have to be formed at the same level. However, the same surface levels are illustrated for ease of description.

Referring to FIG. 4B, a first insulating layer 110 may be entirely formed on a surface of the semiconductor substrate 101, and a first photoresist pattern 155 a exposing the first insulating layer 110 on the peripheral area PA may be formed on the first insulating layer 110. In succession, in the peripheral area PA, an exposed portion of the first insulating layer 110 may be partially removed and formed into a peripheral transistor insulating layer 110 a. In an example of this embodiment, the first insulating layer 110 is formed of thermal silicon oxide using thermal deposition methods and to a thickness of about 500 Å. The thermal deposition methods may be performed in a range of about 600° C. to 1000° C. The peripheral transistor insulating layer 110 a may be variously formed in compliance with standards of semiconductor devices. In the example, the peripheral transistor insulating layer 110 a is formed to a thickness of about 50 Å. Then, the photoresist pattern 155 a may be removed.

Referring FIG. 4C, a first silicon layer 115 and a second insulating layer 120 may be entirely formed. The first silicon layer 115 may be formed to a thickness of about 400 Å. About 100 Å of an upper portion of the first silicon layer 115 may include carbon. Even if there are no descriptions relating to carbon in the examples of embodiments of the inventive concepts, it should be understood that any silicon layers may include carbon in their upper portions. Specifically, any silicon layers to be formed in gate electrodes of the peripheral transistor in the peripheral area PA may include a carbon-containing layer and a non carbon-containing layer. The first silicon layer 115 including carbon will be described in more detail later.

In any case, the first silicon layer 115 may be used to form a gate electrode of the peripheral transistor in the peripheral area PA. Accordingly, an ion injecting process may be performed to make the first silicon layer 115 conductive. For example, N-type impurities may be injected in a step of forming the first silicon layer 115 and P-type impurities may be injected after the step of forming the first silicon layer 115. The process of injecting P-type impurities may include forming an ion injecting mask pattern to expose areas of the first silicon layer 115 to be injected with P-type impurities and injecting the P-type impurities into the exposed areas using the ion injecting mask pattern. Even if the ion injecting process is not mentioned in the description of other embodiments, the ion injecting process can be applied to such embodiments.

The second insulating layer 120 may be formed to a thickness of about 700 Å using silicate insulating materials such as tetraethyl orthosilicate (TEOS).

Referring to FIG. 4D, a bit line contact hole 160 h may be formed. Forming the bit line contact hole 160 h may include entirely forming a second photoresist pattern 155 b on the second insulating layer 120 and patterning the second insulating layer 120, the first silicon layer 115, and the first insulating layer 110 using the second photoresist pattern 155 b as a patterning mask. As shown in FIG. 4D, the bottom of the bit line contact hole 160 h may be formed beneath the surface of the semiconductor substrate 101. In addition, an SOH layer may be included between the second photoresist pattern 155 b and the second insulating layer 120. The SOH may include organic resin such as that of a photoresist. The SOH can improve a planarization property, etching resistance property, anti-reflection property, etc. of a photoresist. In embodiments according to the inventive concepts, any photoresist pattern may include an SOH layer. The SOH layer may be removed by the same methods as methods of removing any photoresist. Successively, the second photoresist pattern may be removed. A silicon treatment process may be performed before removing the second photoresist pattern 155 b. The silicon treatment process may make a silicon surface in good condition by lightly etching or cleaning the exposed surface of the semiconductor substrate. In general, during the silicon treatment process, a material to be treated may be slightly removed, for example, less than about 100 Å. The silicon treatment process may be performed after forming a contact hole in other embodiments. After removing the second photoresist pattern 155 b, an ozone strip process to remove by-products, residues of the second photoresist pattern 155 b and the SOH and/or other materials may be performed. The ozone strip process may be performed in a plasma chamber using ozone plasma. Then, a cleaning process to remove any native oxides and/or any contaminating substances may be performed. For example, the cleaning process may include a wet cleaning process for about 10 seconds using an SC-1 solution and/or for about 180 seconds using a diluted fluoric acid solution. The SC-1 solution may include hydrogen peroxide (H₂O₂), ammonia (NH₄OH), and de-ionized water in various ratios and the diluted fluoric acid solution may include fluoric acid and water in various ratios.

Referring to FIG. 4E, a second silicon layer 125 may be formed to a thickness of about 1000 Å to completely fill the bit line contact hole 160 h.

Referring to FIG. 4F, a CMP process or etch back process may be performed to form the second silicon layer 125 into a bit line contact plug 160 p. Simultaneously, the overall thickness of the second insulating layer 120 may be thinned and the second insulating layer 120 may be formed into a second thinned insulating layer 120 a. An upper surface of the bit line contact plug 160 p may be formed level with or lower than a surface of the second thinned insulating layer 120 a.

Referring to FIG. 4G, a third insulating layer 130 may be entirely formed. The third insulating layer 130 may be formed of silicon oxide to a thickness of about 2000 Å. In the case in which the third insulating layer 130 is of the same material as the underlying layer, i.e., the second thinned insulating layer 120 a, an interface between the second thinned insulating layer 120 a and the third insulating layer 130 is practically indiscernable. Thus, such an interface will be illustrated using broken lines. That is, it can be said, that once the third insulating layer 130 is realized, any discernable interface between the layers 130 and 120 a “no longer exists”. When the second thinned insulating layer 120 a and the third insulating layer 130 are formed of different materials, a discernable interface will of course exist.

Referring to FIG. 4H, surfaces of the bit line contact plug 160 p and the first silicon layer 115 may be exposed by entirely removing the third insulating layer 130 using a CMP method and an etch back method. A first planarized silicon layer 115 a may be formed in the cell area CA and a third planarized insulating layer 130 a may remain in the peripheral area PA. Specifically, a top surface level of the first planarized silicon layer 115 a in the cell area CA and a top surface level of the third planarized insulating layer 130 a in the peripheral area PA may be similar to each other. As a result of the process, the first planarized silicon layer 115 a may be thinner than the first silicon layer 115. The second thinned insulating layer 120 a may be formed into a second thinned peripheral insulating layer 120 b in the peripheral area PA.

Referring to FIG. 4I, a first peripheral silicon layer 115 b may be formed by removing an upper portion of the bit line contact plug 160 p and the first planarized silicon layer 115 a in the cell area CA. A second twice-thinned peripheral insulating layer 120 c may be formed by removing about 100 Å of an upper portion of the second thinned peripheral insulating layer 120 b in the peripheral area PA. The top surface of the bit line contact plug 160 p may be lower than the top surface of the first insulating layer 110 in the cell area CA. In FIG. 4I, the top surface level of the bit line contact plug 160 p and the top surface level of the first insulating layer 110 are shown coplanar simply for ease of description and understanding.

Referring to FIG. 4J, by removing portions of the first insulating layer 110 and the second thinned peripheral insulating layer 120 c using a wet etching method, a first thinned cell insulating layer 110 b may be formed in the cell area CA and the first peripheral silicon layer 115 b may be exposed in the peripheral area PA. In the results of performing the process, the bit line contact plug 160 p may protrude from the top of the first thinned cell insulating layer 110 b in the cell area CA. The first peripheral silicon layer 115 b may protrude from the top of the first thinned cell insulating layer 110 b in the peripheral area PA. In the process, the process recipes may be optimized such that the top surface of the bit line contact plug 160 p may be level with or lower than the surface of the first thinned cell insulating layer 110 b. The optimized process will be described in other example embodiments. In addition, a removed amount of the first insulating layer 110 or a height difference between the surface of the first insulating layer 110 and the top surface of the bit line contact plug 160 p may be adjusted to about 200 Å.

Referring to FIG. 4K, an interconnection layer 170 may be formed. The interconnection layer 170 may include a lower metal layer 172, a barrier layer 174 a, an upper metal layer 174 b, an interconnection electrode layer 176 and an interconnection capping layer 178. The lower metal layer 172 may be formed into a metal silicide layer by silicidation reacting on the bit line contact plug 160 p and the first peripheral silicon layer 115 b. That is, the lower metal layer 172 may be a metallic layer for forming a metal silicide layer. The lower metal layer may be formed to a thickness of about 80 Å. The barrier layer 174 a may comprise a titanium nitride (TiN) layer. The upper metal layer 174 b may comprise a metal silicide layer or a metallic layer for forming the metal silicide layer. The total thickness of the barrier layer 174 a and the upper metal layer 174 b may be about 100 Å. In any of the embodiments, the upper metal layer 174 b may be omitted.

The interconnection electrode layer 176 may be formed into a bit line in the cell area CA and a gate metal electrode corresponding to an upper electrode of a peripheral transistor in the peripheral area PA. The interconnection electrode layer 176 may comprise at least one of tungsten (W), copper (Cu), cobalt (Co), nickel (Ni), ruthenium (Ru), iridium (Ir), or other metals. The interconnection electrode layer 176 may be formed to a thickness of about 500 Å. The interconnection capping layer 178 may comprise a layer of silicon nitride having a thickness of about 1300 Å. The above thicknesses are not absolute but relative in accordance with the disclosed embodiment.

Referring to FIG. 4L, by performing a patterning process, a bit line pattern 170BL may be formed in the cell area CA and a peripheral transistor pattern 170PT may be formed in the peripheral area PA. Broken lines in FIG. 4L illustrate the obliqueness of the bit line pattern 170BL (as shown in FIG. 1a ). The patterning process may include a photolithography process and an etching process. Then, by performing a process to form a wrapping layer, any one of the semiconductor devices illustrated in FIGS. 2A to 3C may be fabricated. In succession, an interlayer dielectric layer covering the bit line pattern 170BL and the peripheral transistor pattern 170PT, and storage contacts may be further formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 2

Referring to FIG. 5A, by performing the processes shown in FIGS. 4A and 4B, a first cell insulating layer 210 may be formed to a thickness of about 1000 Å and a first peripheral insulating layer 210 a to a thickness of about 50 Å.

Referring to FIG. 5B, a first silicon layer 215 and a second insulating layer 220 may be entirely formed. The first silicon layer 215 may include a first lower silicon layer 216 not containing carbon and a first upper silicon layer 217 containing carbon. When a portion of the first silicon layer 215 includes carbon, etching resistance of the first silicon layer 215 can be improved. The first upper silicon layer 217 containing carbon may be formed by supplying carbon ions during any process for forming the first silicon layer 215, or by injecting carbon into the first silicon layer 215 using diffusion methods or implantation methods after forming the first silicon layer 215. The first lower silicon layer 216 may be formed to a thickness of about 300 Å and the first upper silicon layer 217 may be formed to a thickness of about 100 Å. When the first silicon layer 215 in the peripheral area PA is a gate electrode of a PMOS transistor, a process of injecting P-type impurities may be performed before forming the second insulating layer 220. The second insulating layer 220 may be formed of silicon nitride to a thickness similar to that of the first silicon layer 215.

Referring to FIG. 5C, a first photoresist pattern 255 a exposing the cell area CA and covering a portion of the peripheral area PA may be formed. A second peripheral insulating layer 220 a in the cell area CA may be formed by selectively removing exposed portions of the second insulating layer 220 using the first photoresist pattern 255 a as a patterning mask. The first silicon layer 215 may be exposed in the cell area CA. A wet etching process using phosphoric acid (H₃PO₄) may be used to selectively remove the exposed portion of the second insulating layer 220. Then, the first photoresist pattern 255 a may be removed.

Referring to FIG. 5D, a bit line contact hole 260 h may be formed by forming a second photoresist pattern 255 b entirely on the first silicon layer 215 and the second peripheral insulating layer 220 a, and selectively removing portions of the first silicon layer 215, the first insulating layer 210, and the semiconductor substrate 201. Then, a silicon treatment process, removal of the second photoresist pattern 255 b, an ozone treatment process, and/or a cleaning process may be performed.

Referring FIG. 5E, a second silicon layer 225 may be entirely formed to a sufficient thickness to fill the bit line contact hole 260 h. For example, the second silicon layer 225 may be formed to a thickness of about 1000 Å from a top surface of the first silicon layer 215 or the second peripheral insulating layer 220 a.

Referring to FIG. 5F, by planarizing the second silicon layer 225 using a CMP process and/or an etch back process, a bit line contact plug 260 p may be formed in the cell area CA and a second thinned peripheral insulating layer 220 b and a first peripheral silicon layer 215 a for a gate electrode of a peripheral transistor may be formed in the peripheral area PA. Here, top surfaces of the bit line contact plug 260 p and the first peripheral silicon layer 215 a may be level with or lower than a top surface of the first insulating layer 210.

Referring to FIG. 5G, an interconnection layer 270 may be formed as shown in FIG. 4K. In an example of this embodiment, in which the top surface of the bit line contact plug 260 p is lower than the top surface of the first insulating layer 210, elements of the interconnection layer 270 may have recessed or curved shapes. Then, by performing the processes of FIGS. 4K and 4L, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 3

Referring to FIG. 6A, by performing any processes shown in FIGS. 4A and 4B, a first insulating layer 310, a first silicon layer 315, and a second insulating layer 320 may be formed. The first insulating layer 310 may be formed of silicon oxide to a thickness of about 600 Å. The first silicon layer 315 may be formed to a thickness of about 400 Å and include a carbon-containing layer. The second insulating layer 320 may be formed to a thickness of about 700 Å using silicon oxide, e.g., TEOS.

Referring to FIG. 6B, a bit line contact hole 360 h may be formed by forming a photoresist pattern 355 on the second insulating layer 320 and patterning the second insulating layer 320, the first silicon layer 315, and the first insulating layer 310 using the photoresist pattern 355 as a patterning mask. An SOH layer 353 may be formed between the photoresist pattern 355 and the second insulating layer 320. FIG. 6B illustrates one shape of the SOH layer 353. Then, a silicon treatment process, a removing process to remove the photoresist pattern 355 and the SOH layer 353, an ozone treatment process and/or a cleaning process may be performed.

Referring to FIG. 6C, a second silicon layer 325 may be formed to a thickness of about 1000 Å to sufficiently fill the bit line contact hole 360 h.

Referring to FIG. 6D, a bit line contact plug 360 p may be formed by planarizing the second silicon layer 325 using a CMP process and/or etch back process. As a result of the process, the top surface of the second insulating layer 320 may be exposed. Top surfaces of the bit line contact plug 360 p and the first silicon layer 315 do not have to be at the same level. However, the same surface levels are illustrated so that the inventive concepts may be easily understood.

Referring to FIG. 6E, the top surface of the first silicon layer 315 may be exposed by removing the second insulating layer 320 using an etch back process and/or wet etching processes.

Referring to FIG. 6F, a second insulating layer 330 may be formed of silicon nitride to a thickness of about 2000 Å.

Referring to FIG. 6G, the third insulating layer 330 may be planarized and/or removed using CMP and/or etch back processes. In the results of the process, the first silicon layer 315 may be exposed in the cell area CA and the third peripheral insulating layer 330 a may remain in the peripheral area PA. The first silicon layer 315 may be formed into a first thinned silicon layer 315 a by partially removing the top surface of the first silicon layer 315. The first thinned silicon layer 315 may be situated at a level similar to that of the third peripheral insulating layer 330 a.

Referring to FIG. 6H, the first insulating layer 310 may be exposed after removing the first thinned silicon layer 315 a using CMP and/or etch back processes. In the results of the process, an upper portion of the first insulating layer 310 may be partially removed. That is, the first insulating layer 310 may be lightly thinned overall. The third thinned peripheral insulating layer 330 b may remain in the peripheral area PA.

Referring to FIG. 6I, an interconnection layer 370 may be formed by removing the third thinned peripheral insulating layer 330 b remaining in the peripheral area PA. The processes for forming the interconnection layer 370 and subsequent processes may be understood by referring to the foregoing descriptions of the other embodiments. Then, the processes shown in FIG. 4L may be performed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 4

Referring to FIG. 7A, a first insulating layer 410, a first silicon layer 415, and a second insulating layer may be formed by performing the processes shown in FIGS. 4A and 4B. The first insulating layer may be formed to a thickness of about 800 Å and include thermal silicon oxide formed under a temperature of 600° C. to 1000° C. The first silicon layer 415 may be formed to a thickness of about 400 Å and include a carbon-containing layer. The second insulating layer 420 may be formed to a thickness of about 700 Å and include silicon nitride.

Referring to FIG. 7B, by removing the second insulating layer 420 and the first silicon layer 415 using CMP and/or etch back processes, the first insulating layer 410 may be exposed in the cell area CA, and the first peripheral silicon layer 415 a and the second peripheral insulating layer 420 a may remain in the peripheral area PA. Top surfaces of the first peripheral silicon layer 415 a and the first insulating layer 410 do not have to be formed at the same level. However, the surfaces are illustrated as formed at the same level for ease of description.

Referring to FIG. 7C, a bit line contact hole 460 h may be formed by forming a photoresist pattern 455 and patterning the first insulating layer 410 using the photoresist pattern 455 as a patterning mask. In an example of this embodiment, the photoresist pattern 455 includes an SOH layer. Then, a silicon treatment process, a removing process to remove the photoresist pattern 455, an ozone treatment process, and/or a cleaning process may be performed.

Referring to FIG. 7D, a second silicon layer 425 may be formed to a thickness of about 1000 Å to fill the bit line contact hole 460 h.

Referring to FIG. 7E, a bit line contact plug 460 p may be formed by partially removing the second silicon layer 425 using CMP and/or etch back processes. As a result of these or subsequent processes, the second peripheral insulating layer 420 a may be completely removed and the first peripheral silicon layer 415 a to be formed as a gate electrode of peripheral transistors may remain in portions of the peripheral area PA. A top surface of the bit line contact plug 460 p may be level with or lower than the top surface of the first insulating layer 410. A top surface of the first peripheral silicon layer 415 a remaining in the peripheral area PA may also be level with or lower than the top surface of the first insulating layer 410. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 5

Referring to FIG. 8A, a first insulating layer 510, a first silicon layer 515, and a second insulating layer may be formed by performing the processes shown in FIGS. 4A, 4B, and 7A. A photoresist pattern 555 exposing the cell area CA may be entirely formed. Successively, a second thinned insulating layer 520 a may be formed by removing the exposed portions of the second insulating layer in the cell area CA. Then, the photoresist pattern 555 may be removed.

Referring to the FIG. 8B, a second peripheral insulating layer 520 b may remain in the peripheral area PA by removing the second thinned insulating layer 520 a using a CMP process. The first silicon layer 515 may be entirely exposed in the cell area CA. Then, the first silicon layer 515 may be partially removed using a CMP and/or etch back process and formed into a shape similar to that shown in FIG. 7B. Processes similar to those shown in FIGS. 7B to 7E may be subsequently performed.

Embodiment 6

Referring to FIG. 9A, after performing any processes shown in FIG. 4A, a first insulating layer 610 may be entirely formed. A first photoresist pattern 655 a that exposes portions of the peripheral area PA may be formed on the first insulating layer 610. A peripheral transistor insulating layer 610 a may be formed by partially removing the first insulating layer 610 in the peripheral area PA using the first photoresist pattern as a patterning mask. The first insulating layer 610 may be formed of silicon oxide to a thickness of about 500 Å. Then, the first photoresist pattern 655 a may be removed.

Referring to FIG. 9B, a first silicon layer 615 and a second insulating layer 620 may be entirely formed. The first silicon layer 615 may be formed to a thickness of about 400 Å and the second insulating layer 620 may be formed of silicon nitride to a thickness of about 500 Å.

Referring to FIG. 9C, a second photoresist pattern 655 b exposing the second insulating layer 620 in the cell area CA may be entirely formed. In succession, the exposed portion of the second insulating layer 620 may be removed using the second photoresist pattern 655 b as an etching mask and formed into a second thinned insulating layer 620 a. Then, the second photoresist pattern 655 b may be removed.

Referring to FIG. 9D, the first silicon layer 615 may be exposed by completely removing the second thinned insulating layer 620 a using CMP and/or etch back processes in the cell area CA. As a result, the second peripheral insulating layer 620 b may remain in the peripheral area PA. Also, the top surface of the first silicon layer 615 may be partially removed.

Referring to FIG. 9E, the first insulating layer 610 may be exposed by removing the first silicon layer 615 exposed in the cell area CA. As a result, a second twice-thinned peripheral insulating layer 620 c and a first peripheral silicon layer 615 a may remain in the peripheral area PA. In this embodiment, the thickness of the second twice-thinned peripheral insulating layer 620 c remaining in the peripheral area PA may be variously formed in accordance with initial thicknesses of any layers and/or processes. Then, processes shown in FIG. 7C and beyond may be performed. Any of the semiconductor devices shown in FIGS. 2A to 3C may be completed by then performing the processes shown FIGS. 4K, 4L, 5G and 61.

Embodiment 7

Referring to FIG. 10A, the processes shown in FIG. 4A may be performed to form a first insulating layer 710, and a first photoresist pattern 755 a exposing portions of the peripheral area PA. In succession, a peripheral transistor insulating layer 710 a may be formed to a thickness of about 100 Å by patterning the first insulating layer 710 using the first photoresist pattern 755 a as a patterning mask. Then, the first photoresist pattern 755 a may be removed.

Referring to FIG. 10B, a first silicon layer 715 and a second insulating layer 720 may be entirely formed to a thickness of about 400 Å. The second insulating layer 720 may be formed of silicon oxide. Specifically, the second insulating layer 720 may be formed to a thickness of about 50 Å using an atomic layer deposition (ALD) method. Material layers formed by ALD can be relatively denser than material layers formed by other methods. Material layers formed by ALD may have higher etch resistance than material layers formed by other methods. Accordingly, the second insulating layer 720 can have an etch selectivity with respect to any insulating layer formed thereafter.

Referring to FIG. 10C, a second photoresist pattern 755 b exposing the first insulating layer 710 in the cell area CA may be formed, and the exposed second insulating layer 720 and the first silicon layer 715 may be removed in the cell area CA. As a result, the first insulating layer 710 exposed in the cell area CA may be completely removed, may remain as a first thinned insulating layer 710 b shown in the drawing, or may remain wholly. Then, the second photoresist pattern 755 b may be removed. In any case, a first peripheral silicon layer 715 a and a second peripheral insulating layer 720 a may be formed only in the peripheral area PA.

Referring to FIG. 10D, a third insulating layer 730 may be entirely formed to a thickness of about 1000 Å and include silicon oxide, e.g., TEOS. When the first thinned insulating layer 710 b and the third insulating layer 730 are formed of the same material, an interface thereof may disappear. In the drawing, the resulting lack of an interface between the first thinned insulating layer 710 b and the third insulating layer 730 is shown as broken lines. The broken lines will be omitted in drawings that follow FIG. 10D.

Referring to FIG. 10E, a third thinned insulating layer 730 a may be formed by partially removing the third insulating layer 730 using a CMP process. As a result of the process, a height difference of the third thinned insulating layer 730 a between the cell area CA and the peripheral area PA may be reduced. For example, removed amounts of the third insulating layer 730 may be about 500 Å in the cell area CA and 600 Å in the peripheral area PA.

Referring to FIG. 10F, a third photoresist pattern 755 c may be formed on the third thinned insulating layer 730 a, and a bit line contact hole 760 h may be formed by patterning the third thinned insulating layer 730 a using the third photoresist pattern 755 c as a patterning mask. Then, the third photoresist pattern 755 c may be removed. Before or after removing the third photoresist pattern 755 c, a silicon treatment process may be further performed. After removing the third photoresist pattern 755 c, an ozone treatment process and/or a cleaning process may be performed.

Referring to FIG. 100, a second silicon layer 725 may be formed to a thickness of about 1000 Å to fill the bit line contact hole 760 h.

Referring to FIG. 10H, a bit line contact plug 760 p may be formed by removing upper portions of the second silicon layer 725 and the third thinned insulating layer 730 a using an etch back process. As a result of the process, a third twice-thinned insulating layer 730 b may be formed. The third twice-thinned peripheral insulating layer 730 c may remain on the first peripheral silicon layer 715 a in the peripheral area PA. Top surfaces of the bit line contact plug 760 p and the third twice-thinned insulating layer 730 b may be situated at the same level. However, the top surface of the bit line contact plug 760 p may be at a level higher or lower than that of the third twice-thinned insulating layer 730 b. That is, the levels of the top surfaces of the bit line contact plug 760 p and the third twice-thinned insulating layer 730 b may vary in accordance with process recipes of the etch back process.

Referring to FIG. 10I, by performing a pre-cleaning process, the third twice-thinned insulating layer 730 b may be formed into a third thrice-thinned insulating layer 730 d and the third twice-thinned peripheral insulating layer 730 c may be removed from the first twice-thinned peripheral silicon layer 715 c. Then, interconnection layers and other elements may be formed by performing sequential processes shown in FIGS. 4K, 4L, 5G, and 61. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 8

Referring to FIG. 11A, by performing processes shown in FIG. 10A, a first insulating layer 810 may be formed. Then, a first silicon layer 815 and a second insulating layer 820 may be entirely formed on the first insulating layer 810. The first silicon layer 815 may be formed to a thickness of about 500 Å and the second insulating layer 820 may be formed of silicon oxide to a thickness of about 200 Å using an ALD process.

Referring to FIG. 11B, a first photoresist pattern 855 a exposing the second insulating layer in the cell area CA may be formed, and exposed portions of the second insulating layer 820 may be removed using the first photoresist pattern 855 a as an etching mask. Then, by removing the first photoresist pattern 855 a, the first silicon layer 815 may be exposed in the cell area CA and a first peripheral insulating layer 820 a may be formed in the peripheral area PA.

Referring to FIG. 11C, the exposed portions of the first silicon layer 815 may be removed using the second peripheral insulating layer 820 a as an etching mask, the first silicon layer 810 may be exposed in the cell area CA and a first peripheral silicon layer 815 a may be formed in the peripheral area PA.

Referring to FIG. 11D, a third insulating layer 830 may be entirely formed to a thickness of about 1200 Å and may comprise silicon oxide, e.g., TEOS. When the first insulating layer 810 and the third insulating layer 830 are formed of the same material, an interface between the first insulating layer 810 and the third insulating layer 830 may disappear in the cell area CA and an interface between the second insulating layer 820 a and the third insulating layer 830 may remain in the peripheral area PA. In the drawing, the interface of the first insulating layer 810 and the third insulating layer 830 is shown as broken lines to indicate that it no longer exists.

Referring to FIG. 11E, a third partially planarized insulating layer 830 a may be formed by planarizing the third insulating layer 830 using a CMP process. A top surface level of the third partially planarized insulating layer 830 a in the peripheral area PA may be higher than a top surface level of the third partially planarized insulating layer 830 a in the cell area CA. As shown in the drawing, the top surface of the third partially planarized insulating layer 830 a may slope in the core area, e.g., the area between the cell area CA and the peripheral area PA. Since elements in the drawing are shown as simplified, the slope is shown as steep, but the slope may be gentle in practice. As a result of the process, the third partially planarized insulating layer 830 a may remain at a thickness of about 720 Å in the cell area CA, and about 620 Å in the peripheral area PA, for example. In addition, the third partially planarized insulating layer 830 a may remain at a thickness of about 370 Å in a weak portion of the core area, for example, a corner area of the first peripheral silicon layer 815 a. The remaining thicknesses may be the total thickness of the first insulating layer 810 and the second peripheral insulating layer 820 a, and an average thickness in each area, respectively. The interface of the first insulating layer 810 and the third partially planarized insulating layer 830 a will be omitted in the drawings that follow.

Referring to FIG. 11F, a bit line contact hole 860 h may be formed by forming a second photoresist pattern 855 b, and patterning the third partially planarized insulating layer 830 a using the second photoresist pattern 855 b as a patterning mask. In succession, the second photoresist pattern 855 b may be removed. A silicon treatment process, an ozone treatment process, and a cleaning process may be performed before or after the second photoresist pattern 855 b is removed. During the silicon treatment process and/or the cleaning process, a third thinned insulating layer 830 b (shown in FIG. 11G) may be formed by removing an upper portion of the third partially planarized insulating layer 830 a at a thickness of about 100 Å.

Referring to FIG. 11G, a second silicon layer 825 may be entirely formed to a thickness of about 1000 Å to fill the bit line contact hole 860 h. In the drawing, a third thinned insulating layer 830 b formed through the silicon treatment process and/or the cleaning process is illustrated.

Referring to FIG. 11H, a bit line contact plug 860 p may be formed by partially removing the second silicon layer 825 using an etch back process. As a result of the process, the third thinned insulating layer 830 b may be formed into a third twice-thinned insulating layer 830 c. A top surface of the bit line contact plug 860 p may be situated at a level lower than that of a top surface of the third twice-thinned insulating layer 830 c. Also, processes for wet etching or cleaning silicon oxide may be performed.

Referring to FIG. 11I, after forming a third photoresist pattern 855 c exposing the third twice-thinned insulating layer 830 c in the peripheral area PA, the third twice-thinned insulating layer 830 c and the second peripheral insulating layer 820 a may be removed in the peripheral area PA by a wet etching process using the third photoresist pattern 855 c as a wet etching mask. As a result of the process, an undercut U1 may occur beneath the third photoresist pattern 855 c in the core area or the peripheral area PA. Then, the third photoresist pattern 855 c may be removed.

Referring to FIG. 11J, a third thrice-thinned insulating layer 830 d may be formed by partially removing a top surface of the third twice-thinned insulating layer 830 c. The removing process may be performed using a dry, wet, and/or cleaning etching process. In the embodiment, for example, the removing process may be a cleaning process. Specifically, the removing may occur by cleaning the top surfaces of the bit line contact plug 860 p and the first peripheral silicon layer 815 a. The cleaning process may use a diluted fluoric acid (HF) solution to remove native oxides remaining on the top surfaces of the bit line contact plug 860 p and the first peripheral silicon layer 815 a. In the process, the surfaces of the third thrice-thinned insulating layer 830 d and the bit line contact plug 860 p may become the same or similar to each other. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 9

Referring to FIG. 12A, by performing the processes shown in FIGS. 11A to 11C, a first insulating layer 910, a first peripheral silicon layer 915, a second peripheral insulating layer 920, and a third insulating layer 930 may be formed. The second peripheral insulating layer 920 may be formed to a thickness of about 50 Å. The third insulating layer 930 may be formed of silicon oxide, e.g., TEOS to a thickness of about 1000 Å. An interface between the first insulating layer 910 and the third insulating layer 930 will be omitted in drawings that follow FIG. 12A.

Referring to FIG. 12B, a third partially planarized insulating layer 930 a may be formed by performing a CMP process. The third partially planarized insulating layer 930 a may be thicker than the third partially planarized insulating layer 830 a shown in FIG. 11E. For example, the third partially planarized insulating layer 930 a may remain at a thickness of about 800 Å in the cell area CA, about 750 Å in the peripheral area PA, and about 600 Å in the core area.

Referring to FIG. 12C, after forming a second photoresist pattern 955 b, a bit line contact hole 960 h may be formed by patterning the third partially planarized insulating layer 930 a using the second photoresist pattern 955 b as a patterning mask. In addition, as a result of the process, the third partially planarized insulating layer 930 a may be hardly thinned or not at all. This shows that the inventive concepts may be selectively applied.

Referring to FIG. 12D, a second silicon layer 925 may be entirely formed to a thickness of 1000 Å.

Referring to FIG. 12E, a bit line contact plug 960 p may be formed. As a result of the process, the third partially planarized insulating layer 930 a may be formed into a third thinned insulating layer 930 b. That is, in the process, an etching process or a cleaning process to partially remove oxide materials may be performed. Furthermore, a top surface of the bit line contact plug 960 p may be situated at a level lower than that of a top surface of the third thinned insulating layer 930 b.

Referring to FIG. 12F, after forming a third photoresist pattern 955 c, the third thinned insulating layer 930 b and the second peripheral insulating layer 920 of the peripheral area PA may be removed using the third photoresist pattern 955 c as an etching mask. As a result of the process, an undercut U2 may occur beneath the third photoresist pattern 955 c in the core area or the peripheral area PA. Then, the third photoresist pattern 955 c may be removed.

Referring to FIG. 12G, a third twice-thinned insulating layer 930 c may be formed by partially removing a top surface of the third thinned insulating layer 930 b. Levels of the top surfaces of the third twice thinned insulating layer 930 c and the bit line contact plug 960 p may become similar to each other, i.e., the top surfaces of the third twice thinned insulating layer 930 c and the bit line contact plug 960 p may become substantially coplanar. Then, by performing the processes shown in FIGS. 4K, 4L, 5G, and 61, interconnection layers may be formed. In this ways, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 10

Referring to FIG. 13A, by performing the processes shown in FIGS. 11A to 11C, and 12A, a first insulating layer 1010, a first peripheral silicon layer 1015, and a second peripheral insulating layer 1020 may be formed. Then, the third insulating layer 1030 and the fourth insulating layer 1040 may be formed. The third insulating layer 1030 may be formed of silicon oxide to a thickness of about 600 Å and the fourth insulating layer 1040 may be formed of silicon nitride to a thickness of about 600 Å. An interface between the first insulating layer 1010 and the third insulating layer 1030 is illustrated in broken lines. The interface between the first insulating layer 1010 and the third insulating layer 1030 will be omitted in drawings that follow FIG. 13A.

Referring to FIG. 13B, by performing a planarization process, e.g., a CMP process, a fourth planarized insulating layer 1040 a may be formed in the cell area CA and a third upper portion-planarized insulating layer 1030 a may formed in the peripheral area PA.

Referring to FIG. 13C, after forming a second photoresist pattern 1055 b, a bit line contact hole 1060 h may be formed by pattering the fourth planarized insulating layer 1040 a and the third upper portion-planarized insulating layer 1030 a using the second photoresist pattern 1055 b as a patterning mask. Then the second photoresist pattern 1055 b may be removed. Before or after removing the second photoresist pattern 1055 b, a silicon treatment process may be performed. After removing the second photoresist pattern 1055 b, an ozone treatment process and a cleaning process may be further performed.

Referring to FIG. 13D, a second silicon layer 1025 may be formed to a thickness of about 1000 Å to fill the bit line contact hole 1060 h.

Referring to FIG. 13E, a bit line contact plug 1060 p may be formed by removing the second silicon layer 1025 on the third upper portion-planarized insulating layer 1030 a using an etch back process. As a result of the process, the fourth planarized insulating layer 1040 a may be removed completely. Furthermore, the third upper portion-planarized insulating layer 1030 a may be formed into third thinned insulating layer 1030 b.

Referring to FIG. 13F, the third thinned insulating layer 1030 b remaining in the peripheral area PA may be removed. As a result of the process, the level of a surface of the thinned insulating layer 1030 c in the cell area CA may be similar to the level of a surface of the bit line contact plug 1060 p. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 11

Referring to FIG. 14A, by performing the processes referring to FIGS. 11A to 11C and 12A, a first insulating layer 1110, a first peripheral silicon layer 1115, and a second peripheral insulating layer 1120 may be formed. In succession, a third insulating layer 1130 may be entirely formed. The third insulating layer 1130 may be formed to a thickness of about 800 to 1200 Å and comprise an oxide, e.g., TEOS or a flowable chemical vapor deposition (F-CVD) oxide. An interface between the first insulating layer 1110 and the third insulating layer 1130 will be omitted in drawings that follow FIG. 14A.

Referring to FIG. 14B, after forming a second photoresist pattern 1155 b on the third insulating layer 1130, a bit line contact hole 1160 h may be formed by patterning the third insulating layer 1130 using the second photoresist pattern 1155 b as a patterning mask. Then, the second photoresist pattern 1055 b may be removed.

Referring to FIG. 14C, a second silicon layer 1125 may be entirely formed to a thickness of about 1000 Å to completely fill the bit line contact hole 1160 h.

Referring to FIG. 14D, a bit line contact plug 1160 p may be formed by partially or entirely removing the second silicon layer 1125, the third insulating layer 1130, and the second peripheral insulating layer 1020 using CMP or etch back processes. The third insulating layer 1130 may be formed into a third thinned insulating layer 1130 a in the cell area CA, and the first silicon layer 1115 may be exposed in the peripheral area PA. The planarizing processes for removing the second silicon layer 1125, the third insulating layer 1130 and the second insulating layer 1120 may be performed sequentially or simultaneously. The results of the CMP process can vary according to characteristics of slurries. Accordingly, any of various processes may be combined to obtain results similar to those shown in the drawing. In addition, a cleaning process may be performed after the CMP process or the etch-back process. Then, by performing the processes referring FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 12

Referring to FIG. 15A, after forming a first insulating layer 1210 by performing the processes shown in FIG. 10A, a first silicon layer 1215 and a second insulating layer 1220 may be entirely formed. The first silicon layer 1215 may be formed to a thickness of about 400 Å. The second insulating layer 1220 may be formed of silicon oxide to a thickness of about 200 Å by performing an ALD process.

Referring to FIG. 15B, after forming a first photoresist pattern 1255 a exposing the second insulating layer 1220 in the cell area CA, a second peripheral insulating layer 1220 a may be formed by removing the exposed second insulating layer 1220 using the first photoresist pattern 1255 a as a patterning mask. Then, by removing the first photoresist pattern 1255 a, the first silicon layer 1215 may be exposed in the cell area CA and a second peripheral insulating layer 1220 a may be exposed in the peripheral area PA.

Referring to FIG. 15C, a first peripheral silicon layer 1215 a may be formed by removing the exposed first silicon layer 1215 in the cell area CA using the second peripheral insulating layer 1220 a as a patterning mask. The first insulating layer 1210 may be exposed in the cell area CA. The second peripheral insulating layer 1220 a may be thinned during the removing process. That is, the second peripheral insulating layer 1220 a may be formed into a second thinned peripheral insulating layer 1220 b.

Referring to FIG. 15D, a third insulating layer 1230 may be entirely formed of silicon oxide to a thickness of about 1200 Å. In the drawing, an interface between the first insulating layer 1210 and the third insulating layer 1230 are shown as broken lines to indicate that it no longer exists. The broken lines will be omitted in the drawings that follow FIG. 15D.

Referring to FIG. 15E, after forming a second photoresist pattern 1255 b exposing the third insulating layer 1230 in the peripheral area PA, a third partially etched insulating layer 1230 a may be formed by partially etching the exposed third insulating layer 1230 using the second photoresist pattern 1255 b as a patterning mask. The surface levels of the third partially etched insulating layer 1230 a may be similar in the cell area CA and the peripheral area PA. Then the second photoresist pattern 1255 b may be removed.

Referring to FIG. 15F, the third partially etched insulating layer 1230 a may be formed into a third planarized insulating layer 1230 b by a planarizing process, e.g., a CMP process.

Referring to FIG. 15G, after forming a third photoresist pattern 1255 c, a bit line contact hole 1260 h may be formed by patterning the third planarized insulating layer 1230 b using the third photoresist pattern 1255 c as a patterning mask. Then, the third photoresist pattern 1255 c may be removed. A silicon treatment process may be performed before removing the third photoresist pattern 1255 c. An ozone treatment process and a cleaning process may be performed after removing the third photoresist pattern 1255 c.

Referring to FIG. 15H, second silicon layer 1225 may be formed to a thickness of about 1000 Å to completely fill the bit line contact hole 1260 h.

Referring to the FIG. 15I, a bit line contact plug 1260 p may be formed by partially removing the second silicon layer 1225 using CMP or etch back processes. As a result of the process, the third planarized insulating layer 1230 b may be formed into a third thinned insulating layer 1230 c. A top surface of the bit line contact plug 1260 p may be lower than a top surface of the third thinned insulating layer 1230 c.

Referring to FIG. 15J, a third twice-thinned insulating layer 1230 d may be formed by partially or entirely removing the second thinned insulating layer 1230 c and the second peripheral insulating layer 1220 b. Top surfaces of the third twice-thinned insulating layer 1230 d and the bit line contact plug 1260 p may be similar to each other. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 13

Referring to FIG. 16A, by performing the processes shown in FIGS. 15A to 15D, a first insulating layer 1310, a first silicon layer 1315, and a second insulating layer 1320 may be formed. Then, a third insulating layer 1330 may be formed by performing a planarizing process, e.g., a CMP process. After performing the planarizing process, the third insulating layer 1330 may remain at a thickness of about 800 Å in the cell area CA and relatively thicker in the peripheral area PA. An interface between the first insulating layer 1310 and the third insulating layer 1330 is shown in broken lines to indicate that it no longer exists. The broken lines will be omitted in the drawings that follow FIG. 16A.

Referring to FIG. 16B, after forming a first photoresist pattern 1355 a, a bit line contact hole 1360 h may be formed by patterning the third insulating layer 1330 using the first photoresist pattern 1355 a as a patterning mask. Then, the first photoresist pattern 1355 a may be removed. A silicon treatment process may be performed before removing the first photoresist pattern 1355 a.

Referring to FIG. 16C, a second silicon layer 1325 may be formed to a thickness of about 1000 Å to completely fill the bit line contact hole 1360 h.

Referring to FIG. 16D, a bit line contact plug 1360 p may be formed by removing the second silicon layer 1325 using an etch back process. The third insulating layer 1330 may be formed into a third thinned insulating layer 1330 a. The level of the top surface of the bit line contact plug 1360 p may be lower than that of the top surface of the third thinned insulating layer 1330 a.

Referring to FIG. 16E, after forming a second photoresist pattern 1355 b exposing the third thinned insulating layer 1330 a in the peripheral area PA, the first silicon layer 1315 may be exposed by removing the exposed portion of the third thinned insulating layer 1330 a. As a result of the process, an undercut U3 may occur beneath end portions of the second photoresist pattern 1355 b in the core area or the peripheral area PA. The third thinned insulating layer 1330 a may be formed into a third cell insulating layer 1330 b in the cell area CA. Then, the second photoresist pattern 1355 b may be removed.

Referring to FIG. 16F, a top surface of the third cell insulating layer 1330 b may be entirely removed to completely expose the top surface of the first silicon layer 1315 in the peripheral area PA. As a result of the process, the third cell insulating layer 1330 b may be formed into a third thinned cell insulating layer 1330 c. This process may also comprise a cleaning process. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 14

Referring to FIG. 17A, after forming a first insulating layer 1410, a first silicon layer 1415, and a second insulating layer 1420, by performing the processes shown in FIGS. 15A to 15D, a third insulating layer 1430 and a planarizing material layer 1450 may be entirely formed. The third insulating layer 1430 may be formed of silicon oxide to a thickness of about 800 to 1000 Å. The planarizing material layer 1450 may be formed to a thickness of 1000 Å or more using a material having good planarizing characteristics. Good planarizing characteristics mean good flowabilty. In an example of this embodiment, the planarizing material layer 1450 includes an organic material, e.g., SOH. An interface between the first insulating layer 1410 and third insulating layer 1430 may be shown in broken lines to indicate that it no longer exists.

Referring to FIG. 17B, a third planarized insulating layer 1430 a may be formed by performing an etch back process. In the process, removing rates of the planarizing material layer 1450 and the third insulating layer 1430 may be similar to each other. As a result of the process, the planarizing material layer 1450 may be completely removed and the third insulating layer 1430 may be partially removed and formed into the third planarized insulating layer 1430 a.

Referring to FIG. 17C, after forming a first photoresist pattern 1455 a, a bit line contact hole 1460 h may be formed by patterning the third planarized insulating layer 1430 a using the first photoresist pattern 1455 a as a patterning mask. Then, the first photoresist pattern 1455 a may be removed. A silicon treatment process may be performed before or after removing the first photoresist pattern 1455 a.

Referring to FIG. 17D, a second silicon layer 1425 may be formed to a thickness of about 1000 Å to fill the bit line contact hole 1460 h.

Referring to FIG. 17E, a bit line contact plug 1460 p may be formed by entirely removing the second silicon layer 1425 using an etch back process. The third planarized insulating layer 1430 a may be formed into a third thinned insulating layer 1430 b. At this time, a top surface of the bit line contact plug 1460 p may be situated at a level lower than that of a top surface of the third thinned insulating layer 1430 b.

Referring to FIG. 17F, upper portions of the third thinned insulating layer 1430 b may be removed to completely expose the top surface of the first silicon layer 1410 in the peripheral area PA. As a result of the process, the third thinned insulating layer 1430 b may be formed into a third twice-thinned insulating layer 1430 c. The surface levels of the bit line contact plug 1460 p and the third thinned insulating layer 1430 c may become similar to each other. The process may comprise a cleaning process. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 15

Referring to FIG. 18A, a first insulating layer 1510 a, a first silicon layer 1515, and a second insulating layer 1520 may be formed by performing processes described above. The first silicon layer 1515 may be formed to a thickness of about 400 Å. The second insulating layer 1520 may be formed of silicon oxide to a thickness of about 700 Å.

Referring to FIG. 18B, after forming a first photoresist pattern 1555 a, a bit line contact hole 1560 h may be formed by patterning the second insulating layer 1520, the first silicon layer 1515 and a first insulating layer 1510 using the first photoresist pattern 1555 a as a patterning mask. Then, the first photoresist pattern 1555 a may be removed. A silicon treatment process may be performed before removing the first photoresist pattern 1555 a.

Referring to FIG. 18C, a second silicon layer 1525 may be entirely formed to a thickness of about 1000 Å to fill the bit line contact hole 1560 h.

Referring to FIG. 18D, by removing the second silicon layer 1525 using an etch back method, the second insulating layer 1520 may be exposed and a first provisional bit line contact plug 1560 p 1 may be formed. A top surface of the first provisional bit line contact plug 1560 p 1 may be situated at a level lower than that of a top surface of the second insulating layer 1520.

Referring to FIG. 18E, by removing the second insulating layer 1520 and partially removing the top surface of the first provisional bit line contact plug 1560 p 1 using an etch back process, the first silicon layer 1515 may be exposed and a second provisional bit line contact plug 1560 p 2 may be formed. As a result, the level of a top surface of the second provisional bit line contact plug 1560 p 2 may become similar to that of the top surface of the first silicon layer 1515.

Referring to FIG. 18F, a third insulating layer 1530 may be entirely formed of silicon oxide to a thickness of about 400 Å.

Referring to FIG. 18G, a second photoresist pattern 1555 b exposing the third insulating layer 1530 in the cell area CA may be formed. Then the exposed third insulating layer 1530 may be removed. As a result of the process, the first silicon layer 1515 and the second provisional bit line contact plug 1560 p 2 may be exposed in the cell area CA, and a third peripheral insulating layer 1530 a may be formed in the peripheral area PA. Then, the third peripheral insulating layer 1530 a may be exposed in the peripheral area PA by removing the second photoresist pattern 1555 b.

Referring to FIG. 18H, the first silicon layer 1515 and the second provisional bit line contact plug 1560 p 2 which are exposed by the third peripheral insulating layer 1530 a in the cell area CA may be partially removed using the third insulating layer 1530 a as a patterning mask. As a result of the process, a bit line contact plug 1560 p may be formed. A first thinned silicon layer 1515 a may remain in the cell area CA. A third thinned peripheral insulating layer 1530 b may remain in the peripheral area PA. Then, a cleaning process may be performed. During the cleaning process, the third thinned peripheral insulating layer 1530 b may be removed and the first silicon layer 1515 a may be exposed in the peripheral area PA. Then, interconnection layers 1570BL may be formed as shown in FIGS. 18I and 18J, and the processes shown in FIGS. 4K, 4L, 5G and 61 may be performed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 16

Referring to FIG. 19A, a first insulating layer 1610, a first silicon layer 1615 and a second insulating layer 1620 may be formed by performing processes described above. The first silicon layer 1615 may be formed to a thickness of about 400 Å. The second insulating layer 1620 may be formed of silicon oxide to a thickness of about 200 Å by performing an ALD process.

Referring to FIG. 19B, a first photoresist pattern 1655 a exposing the second insulating layer 1620 in the cell area CA may be formed. Then, portions of the second insulating layer 1620 exposed by the first photoresist pattern 1655 a are removed using the first photoresist pattern 1655 a as an etching mask so that the only remaining portion of the second insulating layer 1620 is a second peripheral insulating layer 1620 a in the peripheral area PA. Also, as a result of the process, the first silicon layer 1615 may be exposed in the cell area CA. Then, the second peripheral insulating layer 1620 a may be exposed by removing the first photoresist pattern 1655 a.

Referring to FIG. 19C, a first peripheral silicon layer 1615 a may be formed by removing the first silicon layer 1615 exposed in the cell area CA using the second peripheral insulating layer 1620 a as a patterning mask. In the process, the second peripheral insulating layer 1620 a may be used as a patterning mask and formed into a first thinned insulating layer 1620 b. The first insulating layer 1610 may be exposed in the cell area CA.

Referring to FIG. 19D, a third insulating layer 1630 may be formed of silicon oxide to a thickness of about 1000 Å. For example, the third insulating layer 1630 may comprise silicon oxide having a good flowability or planarizing characteristics. An interface between the first insulating layer 1610 and the third insulating layer 1630 may be illustrated using broken lines to indicate that it no longer exists. The broken lines will be omitted in the drawings that follow FIG. 19D.

Referring to FIG. 19E, after forming a second photoresist pattern 1655 b, a bit line contact hole 1660 h may be formed by patterning the third insulating layer 1630 using the second photoresist pattern 1655 b as a patterning mask. Then, the second photoresist pattern 1655 b may be removed. A silicon treatment process may be performed before or after removing the second photoresist pattern 1655 b. An ozone treatment process and/or a cleaning process may be performed after removing the second photoresist pattern 1655 b.

Referring to FIG. 19F, a second silicon layer 1625 may be formed to a thickness of about 1000 Å to completely fill the bit line contact hole 1660 h.

Referring to FIG. 19G, a bit line contact plug 1660 p may be formed by removing the second silicon layer 1625 on the third insulating layer 1630. In the process, a third thinned insulating layer 1630 a may be formed by partially removing upper portions of the third insulating layer 1630. The second thinned insulating layer 1620 b may be exposed in the peripheral area PA. A top surface of the bit line contact plug 1660 p may be situated at a level lower than that of a top surface of the third thinned insulating layer 1630 a.

Referring to FIG. 19H, the third thinned insulating layer 1630 a and the second thinned insulating layer 1620 b may be partially or completely removed. As a result of the process, the third twice-thinned insulating layer 1630 b may be formed in the cell area CA and the first peripheral silicon layer 1615 a may be exposed in the peripheral area PA. The process may also comprise a cleaning process. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 6I, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 17

Referring to FIG. 20A, a first insulating layer 1710, a first silicon layer 1715, and a second insulating layer 1720 may be formed by performing processes described above. The first silicon layer 1715 may be formed to a thickness of about 500 Å. The second insulating layer 1720 may be formed of an LD oxide (e.g., LD-TEOS) to a thickness of about 150 Å by using a low deposition rate (LDR) process. The LD oxide may have a better etching resistance than conventional deposition methods because the LD oxide may be relatively denser than the conventional oxide or oxide made by high deposition rate processes.

Referring to FIG. 20B, after forming a first photoresist pattern 1755 a exposing the second insulating layer 1720 in the cell area CA, the exposed portion of the second insulating layer 1720 may be removed using the first photoresist pattern 1755 a as a patterning mask. As a result of the process, the second insulating layer 1720 may be formed into a second peripheral insulating layer 1720 a in the peripheral area PA, and the first silicon layer 1715 may be exposed in the cell area CA. Then, the first photoresist pattern 1755 a may be removed.

Referring to FIG. 20C, the first silicon layer 1715 exposed in the cell area CA may be removed using the second peripheral insulating layer 1720 a as a patterning mask. As results of the process, the first silicon layer 1715 may be formed into the first peripheral silicon layer 1715 a in the peripheral area PA and the first insulating layer 1710 may be exposed in the cell area CA. The second peripheral insulating layer 1720 a may be formed into a second thinned peripheral insulating layer 1720 b in the peripheral area PA. Also, the second thinned peripheral insulating layer 1720 b may be formed to a thickness of about 100 Å.

Referring to FIG. 20D, a third insulating layer 1730 may be formed of silicon oxide, e.g., LP-TEOS, to a thickness of about 600 Å. The LP-TEOS may be formed by a high deposition rate (HDR) process. Accordingly, the LP-TEOS may be softer and have a lower etch resistance than LD-TEOS. Obtaining etch selectivity is one of the reasons for using the LP-TEOS or LD-TEOS.

Furthermore, LD-TEOS may be substituted for silicon oxide formed by ALD. An interface between the first insulating layer 1710 and the third insulating layer 1730 may be shown in broken lines to indicate that it no longer exists. The broken lines will be omitted in drawings that follow FIG. 20D.

Referring to FIG. 20E, after forming a second photoresist pattern 1755 b, a bit line contact hole 1760 h may be formed by removing the third insulating layer 1730 using the second photoresist pattern 1755 b as a patterning mask. Then, the second photoresist pattern 1755 b may be removed. A silicon treatment process may be performed before or after removing the second photoresist pattern 1755 b.

Referring to FIG. 20F, a second silicon layer 1725 may be formed to a thickness of about 1000 Å to fill the bit line contact hole 1760 h.

Referring to FIG. 20G, a bit line contact plug 1760 p may be formed by removing the second silicon layer 1725 using an etch back process. In the process, the third insulating layer 1730 may be formed into a third thinned insulating layer 1730 a by partially removing upper portions of the third insulating layer 1730. A top surface of the bit line contact plug 1760 p may be situated at a level lower than that of the surface of the third thinned insulating layer 1730 a.

Referring to FIG. 20H, a fourth insulating layer 1740 may be entirely formed on the third thinned insulating layer 1730 a. The fourth insulating layer 1740 may be formed of silicon oxide, e.g., LP-TEOS, to a thickness of about 250 Å. The bit line contact plug 1760 p may be covered by the fourth insulating layer 1740. An interface between the third thinned insulating layer 1730 a and the fourth insulating layer 1740 may be shown in broken lines to indicate that it no longer exists. The broken lines are omitted in drawings that follow FIG. 20H.

Referring to FIG. 20I, after forming a third photoresist pattern 1755 c exposing the fourth insulating layer 1740 in the peripheral area PA, a fourth partially thinned insulating layer 1740 a may be formed by partially removing exposed portions of the fourth insulating layer 1740. The fourth partially thinned insulating layer 1740 a may remain at a thickness of about 150 Å in the peripheral area PA and about 700 Å in the cell area CA. Then, the third photoresist pattern 1755 c may be removed.

Referring to FIG. 20J, a fourth twice-thinned insulating layer 1740 b may be formed by further removing the fourth partially thinned insulating layer 1740 a using an etch back method. The fourth twice-thinned insulating layer 1740 b may not remain in the peripheral area PA. The etch back process may comprise a wet etching process. In the process, the fourth twice-thinned insulating layer 1740 b may be formed by removing the fourth partially thinned insulating layer 1740 a in the cell area CA to a thickness of about 300 Å, for example. Also, as a result of the process, the bit line contact plug 1760 p and the first silicon layer 1715 may be exposed.

Referring to FIG. 20K, a fourth thrice-thinned insulating layer 1740 c may be formed by annealing and cleaning the fourth twice-thinned insulating layer 1740 b. In the process, the fourth thrice-thinned insulating layer 1740 c may be formed by thinning the fourth twice-thinned insulating layer 1740 b to a thickness of about 200 Å. For example, the annealing process may be performed at a temperature of about 900 to 1000° C. for 1 minute or less. Specifically, the annealing process may be performed at a temperature of about 935° C. for 30 seconds. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 18

Referring to FIG. 21A, a first insulating layer 1810, a first silicon layer 1815, and a second insulating layer 1820 may be formed by performing processes described above. The first silicon layer 1815 may be formed to a thickness of about 500 Å. The second insulating layer 1820 may be formed of silicon oxide to a thickness of about 150 Å using an LD-TEOS deposition process. As described above, LD-TEOS is relatively dense. Thus, the LD-TEOS has a high etch selectivity.

Referring to FIG. 21B, after forming a first photoresist pattern 1855 a exposing the second insulating layer 1820 in the cell area CA, exposed portions of the second insulating layer 1820 may be removed using the first photoresist pattern 1855 a as an etching mask. As a result of the process, the second insulating layer 1820 may be formed into a second peripheral insulating layer 1820 a in the peripheral area PA, and the first silicon layer 1815 may be exposed in the cell area CA. Then, the first photoresist pattern 1855 a may be removed to expose the second peripheral insulating layer 1820 a.

Referring to FIG. 21C, the exposed portion of the first silicon layer 1815 may be removed using the second peripheral insulating layer 1820 a as a pattering mask. As a result of the process, the first silicon layer 1815 may be formed into a first peripheral silicon layer 1815 a, the first insulating layer 1810 is exposed in the cell area, and the second peripheral layer 1820 a may be formed into a second thinned peripheral insulating layer 1820 b. The second thinned peripheral insulating layer 1820 b may be formed to a thickness of about 100 Å.

Referring to FIG. 21D, a third insulating layer 1830 may be entirely formed of silicon oxide, e.g., LD-TEOS, to a thickness of about 600 Å. An interface between the first insulating layer 1810 and the third insulating layer 1830 is illustrated using broken lines to indicate that it no longer exists. The broken line will be omitted in the drawings that follow FIG. 21D.

Referring to FIG. 21E, after forming a second photoresist pattern 1855 b, a bit line contact hole 1860 h may be formed by patterning the third insulating layer 1830 using the second photoresist pattern 1855 b as a patterning mask. Then, the second photoresist pattern 1855 b may be removed. A silicon treatment process may be performed before the second photoresist pattern 1855 b is removed.

Referring to the FIG. 21F, a second silicon layer 1825 may be entirely formed to a thickness of about 1000 Å to fill the bit line contact hole 1860 h.

Referring to FIG. 21G, a bit line contact plug 1860 p may be formed by removing the second silicon layer 1825 using an etch back method. In the process, the third insulating layer 1830 may be formed into a third thinned insulating layer 1830 a by removing upper portions of the third insulating layer 1830. A top surface of the bit line contact plug 1860 p may be situated at a level lower than that of a top surface of the third thinned insulating layer 1830 a.

Referring to FIG. 21H, a fourth insulating layer 1840 may be formed of LD-TEOS on the third thinned insulating layer 1830 a to a thickness of about 200 Å. The bit line contact plug 1860 p may be covered by the fourth insulating layer 1840. An interface between the third thinned insulating layer 1830 a and the fourth insulating layer 1840 is illustrated in broken lines to indicate that it no longer exists. The broken lines will be omitted in the drawings that follow FIG. 21H.

Referring to FIG. 21I, after forming a third photoresist pattern 1855 c exposing the fourth insulating layer 1840 in the peripheral area PA, a fourth partially thinned insulating layer 1840 a may be formed by partially removing the exposed portion of the fourth insulating layer 1840 using the third photoresist pattern 1855 c as an etching mask. The thinned portion of the fourth partially thinned insulating layer 1840 a may remain at a thickness of about 150 Å in the peripheral area PA and about 700 Å in the cell area CA. Then, the third photoresist pattern 1855 c may be removed.

Referring to FIG. 21J, a fourth twice-thinned insulating layer 1840 b may be formed by partially removing upper portions of the fourth partially thinned insulating layer 1840 a using an etch back process. The fourth twice-thinned insulating layer 1840 b may be not formed in the peripheral area PA. In other words, the first peripheral silicon layer 1815 a may be exposed in the peripheral area PA. The etch back process may comprise a wet etching process. As a result of the process, the fourth twice-thinned insulating layer 1840 b may be thinner than the fourth partially thinned insulating layer 1840 a with a thickness of about 250 Å, for example. Also, the bit line contact plug 1860 p may be exposed.

Referring to FIG. 21K, by performing a cleaning process, the fourth twice-thinned insulating layer 1840 b may be formed into a fourth thrice-thinned insulating layer 1840 c. As a result of the process, the fourth thrice-thinned insulating layer 1840 c may be thinner than the fourth twice-thinned insulating layer 1840 b with a thickness of about 150□. The cleaning process may be similar to that described with reference to FIG. 20K. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 19

Referring to FIG. 22A, a first insulating layer 1910, a first silicon layer 1915, and a second insulating layer 1920 may be formed by processes described above. The first silicon layer 1915 may be formed to a thickness of about 500 Å. The second insulating layer 1920 may be formed of silicon oxide, e.g., LP-TEOS, to a thickness of about 350 Å.

Referring to FIG. 22B, after forming a first photoresist pattern 1955 a exposing the second insulating layer 1920 in the cell area CA, a second peripheral insulating layer 1920 a may be formed only in the peripheral area PA by removing exposed portions of the second insulating layer 1920 using the first photoresist pattern 1955 a as an etching mask. As a result of the processes, the first silicon layer 1915 may be exposed in the cell area CA. Then, the second peripheral insulating layer 1920 a may be exposed in the peripheral area PA by removing the first photoresist pattern 1955 a.

Referring to FIG. 22C, the exposed portion of the first silicon layer 1915 in the cell area CA may be removed using the second peripheral insulating layer 1920 a as a patterning mask. As a result of the process, the first silicon layer 1915 may be formed into a first peripheral silicon layer 1915 a in the peripheral area PA, and the first insulating layer 1910 may be exposed in the cell area CA. The second peripheral insulating layer 1920 a may be formed into a second thinned peripheral insulating layer 1920 b. Also, the second thinned peripheral insulating layer 1920 b may be formed to a thickness of about 300 Å.

Referring to FIG. 22D, a third insulating layer 1930 may be entirely formed of silicon oxide, e.g., LD-TEOS, to a thickness of about 550 Å. An interface between the first insulating layer 1910 and the third insulating layer 1930 is illustrated in solid lines not only indicating that the interface is discernable but also that the two layers have an etch selectivity.

Referring to FIG. 22E, after forming a second photoresist pattern 1955 b, a bit line contact hole 1960 h may be formed by patterning the third insulating layer 1930 using the second photoresist pattern 1955 b as a patterning mask. Then the second photoresist pattern 1955 b may be removed. A silicon treatment process may be performed before or after removing the second photoresist pattern 1955 b.

Referring to FIG. 22F, a second silicon layer 1925 may be entirely formed to a thickness of about 1000 Å to fill the bit line contact hole 1960 h.

Referring to FIG. 22G, a bit line contact plug 1960 p may be formed by removing the second silicon layer 1925 on the third insulating layer 1930 using an etch back process. As a result of the process, the third insulating layer 1930 may be formed into a third thinned insulating layer 1930 a. The level of a top surface of the bit line contact plug 1960 p may be lower than that of a top surface of the third thinned insulating layer 1930 a. Also, the third thinned insulating layer 1930 a may be formed to a thickness of about 400 Å in the cell area CA and remain at a thickness of about 700 Å in the peripheral area PA.

Referring to FIG. 22H, a fourth insulating layer 1940 may be formed of silicon oxide, e.g., LP-TEOS, to a thickness of about 300 Å. The bit line contact plug 1860 p may be covered with the fourth insulating layer 1940.

Referring to FIG. 22I, after forming a third photoresist pattern 1955 c exposing portions of the fourth insulating layer 1940 in the peripheral area PA, the exposed portions of the fourth insulating layer 1940 and the third thinned insulating layer 1930 a may be completely removed and the second peripheral insulating layer 1920 b may be partially removed. As a result of the process, a third thinned cell insulating layer 1930 b and a fourth cell insulating layer 1940 a may be formed in the cell area CA, and a second partially thinned insulating layer 1920 c may be formed in the peripheral area PA. The second partially thinned insulating layer 1920 c may be formed to a thickness of about 200 Å. Then, the third photoresist pattern 1955 c may be removed.

Referring to FIG. 22J, the fourth cell insulating layer 1940 a and the second partially thinned insulating layer 1920 c may be removed using a wet etching process. The fourth cell insulating layer 1940 a and the second partially thinned insulating layer 1920 c may comprise LP-TEOS and the third thinned cell insulating layer 1930 b may comprise LD-TEOS. Accordingly, the fourth cell insulating layer 1940 a and the second partially thinned insulating layer 1920 c may be selectively removed. In the process, a removing process to entirely remove a thickness of about 400 Å of LP-TEOS may be performed. The third twice-thinned insulating layer 1930 b may remain at a thickness of about 200 Å in the cell area CA.

Referring to FIG. 22K, a third thrice-thinned insulating layer 1930 c may be formed by performing a cleaning process. The protruding insulating layers remaining in the peripheral area PA or core area may be mostly removed because the protruding shape is less etch-resistant than other shapes. The third twice-thinned insulating layer 1930 c may remain at a thickness of about 150 Å. The process may comprise wet cleaning processes using SC-1 and/or diluted HF solution. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 20

Referring to FIG. 23A, after performing a process similar to that shown in FIG. 4A, a first insulating layer 2010 may be formed of silicon oxide, e.g., LP-TEOS, to a thickness of about 1000 Å.

Referring to FIG. 23B, after forming a first photoresist pattern 2055 a, a bit line contact hole 2060 h may be formed by patterning the first insulating layer 2010 using the first photoresist pattern 2055 a as a patterning mask. The first photoresist pattern 2055 a may be removed.

Referring to FIG. 23C, a first silicon layer 2015 may be entirely formed to a thickness of about 1000 Å to fill the bit line contact hole 2060 h.

Referring to FIG. 23D, a bit line contact plug 2060 p may be formed by removing the first silicon layer 2015 on the first insulating layer 2010. As a result of the process, the first insulating layer 2010 may be formed into a first thinned insulating layer 2010 a. A difference between the level of the top surfaces of the bit line contact plug 2060 p and the first thinned insulating layer 2010 a may vary in accordance with the inventive concepts.

Referring to FIG. 23E, a second insulating layer 2020 comprising silicon nitride may be entirely formed to a thickness of about 100 Å.

Referring to FIG. 23F, after forming a second photoresist pattern 2055 b exposing the peripheral area PA, a second cell insulating layer 2020 a and a first cell insulating layer 2010 b may be formed by removing exposed portions of the second insulating layer 2020 and the first insulating layer 2010 a in the peripheral area PA. As a result of the process, a surface of a semiconductor substrate 2001 may be exposed in the peripheral area PA. Then, the second photoresist pattern 2055 b may be removed.

Referring to FIG. 23G, a third insulating layer 2030 and a second silicon layer 2025 may be entirely formed. The third insulating layer 2030 may be used as a gate insulating layer of a peripheral transistor. The third insulating layer 2030 may include thermal silicon oxide. In the example embodiment, the third insulating layer 2030 may be formed to a thickness of about 50 Å. The second silicon layer 2025 may be used as a gate electrode of a peripheral transistor and formed to a thickness of about 400 Å. An interface between the second silicon layer 2010 b and the third insulating layer 2030 is illustrated in broken lines to indicate that it no longer exists. That is, the first cell insulating layer 2010 b and the third insulating layer 2030 may be of the same material.

Referring to FIG. 23H, a fourth insulating layer 2040 of silicon nitride may be entirely formed to a thickness of about 500 Å.

Referring to FIG. 23I, after forming a third photoresist pattern 2055 c exposing the fourth insulating layer 2040 in the cell area CA, a fourth peripheral insulating layer 2040 a may be formed only in the peripheral area PA by removing exposed portions of the fourth insulating layer 2040 in the cell area CA. The second silicon layer 2025 may be exposed at portions where the fourth insulating layer 2040 is removed. Then, the third photoresist pattern 2055 c may be removed.

Referring to FIG. 23J, the fourth peripheral insulating layer 2040 a and the exposed second silicon layer 2025 may be planarized using a CMP process. As a result of the process, the fourth planarized insulating layer 2040 b may remain only in the peripheral area PA. A second peripheral silicon layer 2025 a may be formed only in the peripheral area PA by removing the exposed portion of the second silicon layer 2025 in the cell area CA. The third insulating layer 2030 may be exposed in the cell area CA. In addition, although not shown, the second cell insulating layer 2020 a may be exposed.

Referring to FIG. 23K, the fourth planarized insulating layer 2040 b, the third insulating layer 2030, and the second cell insulating layer 2020 a may be removed. As a result of the process, a first thinned insulating layer 2010 c may be exposed in the cell area CA, and the second peripheral silicon layer 2025 a may be exposed in the peripheral area PA. Then, by performing the processes shown in FIGS. 4K, 4L, 5G and 61, interconnection layers may be formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated.

Embodiment 21

Referring to FIG. 24A, after performing the process shown in FIG. 4A, a first insulating layer 2110 may be entirely formed and a first photoresist pattern 2155 a exposing the first insulating layer 2110 in the cell area CA and covering the peripheral area PA may be formed. The first insulating layer 2110 comprising silicon oxide or another insulator may be formed to a thickness to be used as a gate insulating layer of a peripheral transistor. For example, the first insulating layer 2110 may be formed to a thickness of 50 to 100 Å.

Referring to FIG. 24B, a first peripheral insulating layer 2110 a may be formed by removing the exposed portion of the first insulating layer 2110 in the cell area CA using the first photoresist pattern 2155 a as an etching mask. This process may comprise a wet cleaning process using diluted HF solution. Then, the first photoresist pattern 2155 a may be removed.

Referring to FIG. 24C, a first silicon layer 2115 may be entirely formed to a thickness of about 300 Å. Furthermore, upper portions of the first silicon layer 2115 may include carbon.

Referring to FIG. 24D, after forming a second photoresist pattern 2155 b, by patterning the first silicon layer 2115 using the second photoresist pattern 2155 b as a patterning mask, a mesa pattern 2160 m may be formed in the cell area CA and a first peripheral silicon layer 2115 a may be formed in the peripheral area PA. The mesa pattern 2160 m will be formed into a bit line contact plug in the cell area CA, and the first peripheral silicon layer 2115 a will be formed into a gate electrode of a peripheral transistor in the peripheral area PA. In other words, the second photoresist pattern 2155 b may be used as a patterning mask for patterning the bit line contact plug in the cell area CA and the gate electrode of the peripheral transistor in the peripheral area PA. Then, the second photoresist pattern 2155 b may be removed.

Referring to FIG. 24E, a second insulating layer 2120 of silicon nitride may be entirely conformably formed to a thickness of about 100 Å.

Referring to FIG. 24F, a third insulating layer 2130 comprising silicon oxide may be entirely formed thicker than the second insulating layer 2120. For example, the third insulating layer 2130 may comprise an oxide having relatively better flowability, e.g., an F-CVD oxide, silicate oxide, or TOSZ.

Referring to FIG. 24G, top surfaces of the mesa pattern 2160 m and the first peripheral silicon layer 2115 a may be exposed by performing a planarizing process, e.g., CMP. In the process, the second insulating layer 2120 may be used as a CMP stopper. The second insulating layer 2120 may be formed into a second partially removed insulating layer 2120 a to expose the top surfaces of the mesa pattern 2160 m and the first peripheral silicon layer 2115 a. The third insulating layer 2130 may be formed into a third planarized insulating layer 2130 a. The mesa pattern 2160 m may be the bit line contact plugs in other embodiments.

Referring to FIG. 24H, an interconnection layer 2170 may be formed. The interconnection layer 2170 may include a lower metal layer 2172, a barrier layer 2174 a, an upper metal layer 2174 b, an interconnection electrode layer 2176 and an interconnection capping layer 2178. The lower metal layer 2172 may be formed into a metal silicide layer by performing a silicidation process on the mesa pattern 2160 m and the first peripheral silicon layer 2115 a in the cell area CA. That is, the lower metal layer 2172 may be a metal layer to form a metal silicide layer. The lower metal layer 2172 may be formed to a thickness of about 80 Å. The barrier layer 2174 a may comprise titanium nitride TiN. The upper metal layer 2174 b may be a metal silicide layer or a metal layer to be formed into a metal silicide layer. The barrier layer 2174 a and the upper metal layer 2174 b may be formed to a thickness of about 100 Å. In other embodiments, the upper metal layer 2174 b may be omitted. That is, the upper metal layer 2174 b is formed merely as an example of this embodiment. The interconnection electrode layer 2176 may be formed into a bit line in the cell area CA and a gate metal electrode corresponding to an upper electrode of a peripheral transistor in the peripheral area PA. The interconnection electrode layer 2176 may be of at least one of tungsten (W), copper (Cu), cobalt (Co), nickel (Ni), ruthenium (Ru), iridium (Ir). However, the interconnection electrode layer 2176 may also be of some other metal. The interconnection electrode layer 2176 may be formed to a thickness of about 500 Å. The interconnection capping layer 2178 may be formed of silicon nitride to a thickness of about 1300 Å. Accordingly, it will be understood that the foregoing thicknesses are merely exemplary.

Referring to FIG. 24I, by performing a patterning process, a bit line pattern 2170BL may be formed in the cell area CA and a peripheral transistor pattern 2170PT may be formed in the peripheral area PA. The broken lines indicate an obliqueness of the bit line pattern 2170BL as shown in FIG. 1A. The patterning may comprise a photolithography process and an etching process. Then, a wrapping layer is formed. In this way, any one of the semiconductor devices shown in FIGS. 2A to 3C may be fabricated. In succession, after forming an interlayer dielectric layer covering the bit line pattern 2170BL and the peripheral transistor pattern 2170PT, a storage contact may be formed.

FIG. 25A illustrates an example of a semiconductor module 2300 in accordance with the inventive concepts. The semiconductor module 2300 includes a module board 2310, a plurality of semiconductor devices 2320 or semiconductor packages (at least one of which comprises an embodiment of a semiconductor device in accordance with the inventive concepts) disposed on the module board 2310, and module contact terminals 2330 formed in parallel on one edge of the module board 2310 and electrically connected to the semiconductor devices 2320. The module board 2310 may be a printed circuit board (PCB). Both surfaces of the module board 2310 may be used. That is, the semiconductor devices 2320 may be disposed on front and rear surfaces of the module board 2310. Hence, although FIG. 25A illustrates the semiconductor devices 2320 disposed on the front surface of the module board 2310, this if for illustrative purposes only.

In addition, a separate semiconductor device may be further provided to control the semiconductor devices 2320. Therefore, the single semiconductor module 2300 is not necessarily limited to the number of semiconductor devices 2320 shown in FIG. 25A. Also, the module contact terminals 2330 may be formed of a metal and have oxidation resistance. The module contact terminals 2330 may be arranged according to any of various standards. For this reason, the number of the module contact terminals 2330 has no particular significance.

FIG. 25B illustrates an example of an electronic circuit board 2400 in accordance with the inventive concepts. Referring to FIG. 25B, the electronic circuit board 2400 includes a microprocessor 2420, a main storage circuit 2430 and a supplementary storage circuit 2440 in communication with the microprocessor 2420, an input signal processing circuit 2450 for sending a command to the microprocessor 2420, an output signal processing circuit 2460 for receiving a command from the microprocessor 2420, and a communicating signal processing circuit 2470 for sending/receiving an electric signal to/from another circuit board, disposed on a circuit board 2410. The arrows show paths along which electric signals are transmitted. The microprocessor 2420 can receive and process various electric signals, output the processed results, and control other components of the electronic circuit board 2400. The microprocessor 2420 may be, for example, a central processing unit (CPU) and/or a main control unit (MCU). The main storage circuit 2430 can temporarily store data that is frequently required by the microprocessor 2420 or data before and after processing. Since the main storage circuit 2430 needs a rapid response speed, the main storage circuit 2430 may be constituted by a semiconductor memory. More specifically, the main storage circuit 2430 may be a semiconductor memory, such as a cache memory, or may be constituted by a static random access memory (SRAM), a dynamic random access memory (DRAM), a resistive random access memory (RRAM), and their applied semiconductor memories, for example, a utilized RAM, a ferro-electric RAM, a fast cycle RAM, a phase changeable RAM, and other semiconductor memories. In addition, the main storage circuit 2430 may include a volatile or non-volatile RAM. In this example, the main storage circuit 2430 includes at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The supplementary storage circuit 2440 may be a large capacity storage device, which may be a non-volatile semiconductor memory such as a flash memory, a hard disc drive using a magnetic field, or a compact disc drive using light. The supplementary storage circuit 2440 may be used when a large capacity of data is to be stored, not requiring a rapid response speed. The supplementary storage circuit 2440 may include a random or non-random non-volatile storage device. The supplementary storage circuit 2440 may include at least one semiconductor device or a semiconductor module 2300 in accordance with the inventive concepts. The input signal processing circuit 2450 may convert an external command into an electric signal, or transmit the electric signal transmitted from the exterior to the microprocessor 2420. The command transmitted from the exterior or the electric signal may be an operation command, an electric signal to be processed, or data to be stored. The input signal processing circuit 2450 may be a terminal signal processing circuit for processing a signal transmitted from, for example, a keyboard, a mouse, a touch pad, an image recognition device or various sensors, an image signal processing circuit for processing an image signal input from a scanner or a camera, or various sensors or input signal interfaces. The input signal processing circuit 2450 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The output signal processing circuit 2460 may be a component for transmitting an electric signal processed through the microprocessor 2420 to the exterior. For example, the output signal processing circuit 2460 may be a graphic card, an image processor, an optical converter, a beam panel card, interface circuits having various functions, or the like. The output signal processing circuit 2460 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The communicating signal processing circuit 2470 is a component for directly sending/receiving an electric signal to/from another electronic system or another circuit board, not through the input signal processing circuit 2450 or the output signal processing circuit 2460. For example, the communication circuit 2470 may be a modem, a LAN card, or various interface circuits of a personal computer system. The communication circuit 2470 may include at least one semiconductor device or semiconductor module in accordance with the inventive concepts.

FIG. 25C illustrates an electronic system 2500 including a semiconductor device or a semiconductor module in accordance with the inventive concepts. Referring to FIG. 25C, the electronic system 2500 includes a control unit 2510, an input unit 2520, an output unit 2530, and a storage unit 2540, and may further include a communication unit 2550 and an operation unit 2560. The control unit 2510 can generally control the electronic system 2500 and the respective units. The control unit 2510 may be a CPU or a central control unit, and may include the electronic circuit board 2400. In addition, the control unit 2510 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The input unit 2520 can send an electric command signal to the control unit 2510. The input unit 2520 may be a keyboard, a key pad, a mouse, a touch pad, an image recognition device such as a scanner, or various input sensors. The input unit 2520 may include a semiconductor device or a semiconductor module 2300 in accordance with the inventive concepts. The output unit 2530 can receive an electric command signal from the control unit 2510 and output the results processed by the electronic system 2500. The output unit 2530 may be a monitor, a printer, a beam projector, or various mechanical devices. The output unit 2530 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The storage unit 2540 may be a component for temporarily or permanently storing an electric signal to be processed or already processed by the controller 2510. The storage unit 2540 may be physically or electrically connected or coupled to the control unit 2510. The storage unit 2540 may be a semiconductor memory, a magnetic storage device such as a hard disc, an optical storage device such as a compact disc, or other servers having data storage functions. In addition, the storage unit 2540 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The communication unit 2550 can receive an electric command signal from the control unit 2510 and send/receive an electric signal to/from another electronic system. The communication unit 2550 may be a wired sending/receiving device such as a modem or a LAN card, a wireless sending/receiving device such as a WIBRO interface, an infrared port, etc. In addition, the communication unit 2550 may include at least one semiconductor device or semiconductor module 2300 in accordance with the inventive concepts. The operation unit 2560 may be physically or mechanically operated according to a command of the control unit 2510. For example, the operation unit 2560 may be a mechanically operated component such as a plotter, an indicator, an up/down operator, etc. The electronic system may be a computer, a network server, a network printer or scanner, a wireless controller, a mobile communication terminal, an exchanger, or another electronic system operated by programs.

According to the inventive concepts, capacitance between a bit line and a cell active region can be reduced by increasing a distance between the bit line and the cell active region. Thus, a semiconductor device in accordance with the inventive concepts can consume lower electric power flowing along the bit line and become faster than conventional electric devices. Consequently, electronic performances of a semiconductor module, an electronic circuit board and an electronic system having the semiconductor devices of the inventive concepts can be improved.

Finally, embodiments of the inventive concept have been described above in detail. The inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the embodiments described above. Rather, these embodiments were described so that this disclosure is thorough and complete, and fully conveys the inventive concept to those skilled in the art. For example, the sequence of steps in the embodiments of the methods according to the inventive concepts may vary from those described. That is, in some cases steps that are described as being carried out simultaneously may be carried out sequentially instead and vice versa. Thus, the true spirit and scope of the inventive concept is not limited by the embodiments described above but by the following claims. Therefore, unless otherwise specified in the claims, the order in which various trenches, layers, elements, etc. are described as being formed, or the fact that trenches, layers, elements, etc. are referred to together in connection with being formed, is not limitative. 

What is claimed is:
 1. A semiconductor device comprising: a semiconductor substrate having a first trench and a second trench in a cell area; a first word line electrode in the first trench; a second word line electrode in the second trench; a first word line insulating layer between the semiconductor substrate and the first word line electrode in the first trench; a cell insulating isolation region in the first trench, the cell insulating isolation region extending beneath the first word line electrode; a bit line on the semiconductor substrate; and a peripheral transistor in a peripheral area, the peripheral transistor having a lower electrode and an upper electrode; wherein the bit line and the upper electrode of the peripheral transistor are at the same level.
 2. The semiconductor device of claim 1, wherein a bottom portion of the cell insulating isolation region in the first trench is lower than a bottom portion of a second word line insulating layer in the second trench.
 3. The semiconductor device of claim 2, wherein: the cell insulating isolation region further comprises side portions different from the bottom portion; the bottom portion of the cell insulating isolation region is positioned underneath a bottom of the first word line electrode in the first trench; the side portions are positioned adjacent to side surfaces of the first word line electrode in the first trench; and the bottom portion of the cell insulating region is thicker than at least one of the side portions of the cell insulating region.
 4. The semiconductor device of claim 1, further comprising: a bit line contact plug between the semiconductor substrate and the bit line.
 5. The semiconductor device of claim 4, wherein the bit line contact plug and the lower electrode of the peripheral transistor are at the same level.
 6. The semiconductor device of claim 1, wherein the cell insulating isolation region beneath the first word line electrode in the first trench is thicker than the first word line insulating layer beneath the first word line electrode in the first trench.
 7. The semiconductor device of claim 1, wherein the cell insulating isolation region extends into the semiconductor substrate to be deeper than lowermost portion of the first word line insulating layer.
 8. The semiconductor device of claim 1, wherein the cell insulating isolation region surrounds a bottom of the first word line insulating layer.
 9. The semiconductor device of claim 1, further comprising: a peripheral trench in the peripheral area; and a peripheral insulating isolation region in the peripheral trench, the peripheral insulating region defining a peripheral active region, wherein the peripheral transistor is disposed on the peripheral insulating isolation region and the peripheral active region.
 10. The semiconductor device of claim 9, wherein the peripheral transistor further comprises an insulating layer between the peripheral active region and the lower electrode of the peripheral transistor.
 11. The semiconductor device of claim 1, wherein the bit line comprises: a bit line electrode; and a bit line capping layer capping top and side walls of the bit line electrode, wherein the bit line capping layer is in contact with the word line capping layer.
 12. The semiconductor device of claim 1, further comprising: an interlayer dielectric covering the bit line and the peripheral transistor.
 13. A semiconductor device comprising: a semiconductor substrate; a first trench and a second trench in a cell area; a first electrode and a first insulating layer in the first trench; a second electrode and a second insulating layer in the second trench; an isolation region beneath the first electrode in the semiconductor substrate; a bit line contact plug between the first trench and the second trench on the semiconductor substrate; a bit line on the bit line contact plug; and a peripheral transistor on the semiconductor substrate in a peripheral area, the peripheral transistor having a lower electrode and an upper electrode on the lower electrode, wherein the bit line contact plug and the lower electrode of the peripheral transistor are at the same level, and wherein the bit line and the upper electrode of the peripheral transistor are at the same level.
 14. The semiconductor device of claim 13, wherein: the first insulating layer is disposed between the first electrode and the semiconductor substrate; and the second insulating layer is disposed between the second electrode and the semiconductor substrate.
 15. The semiconductor device of claim 13, wherein the isolation region is thicker than the first insulating layer.
 16. The semiconductor device of claim 13, wherein: the first and second electrodes extend in a line-shaped in the first and second trenches, respectively.
 17. The semiconductor device of claim 13, wherein the first insulating layer and the second insulating layer have a similar thickness.
 18. A semiconductor device comprising: a semiconductor substrate having first trenches and second trenches between the first trenches; first word lines in the first trenches and second word lines in the second trenches, the first word lines including first word line insulating layers and first word line electrodes in the first trenches, and the first word line insulating layers being between the first word line electrodes and the semiconductor substrate; isolation regions extending at least beneath the first word lines, the isolation regions extending in line-shapes in a first direction, and the isolation regions being deeper than the first word line insulating layers beneath the first word line electrodes; a plug on the semiconductor substrate, the plug being disposed between the second trenches; a bit line on the plug; and a transistor having a lower gate electrode and an upper gate electrode on the semiconductor substrate; wherein the bit line and the upper gate electrode of the transistor are disposed at the same level.
 19. The semiconductor device of claim 18, wherein the plug and the lower gate electrode are disposed at the same level.
 20. The semiconductor device of claim 18, wherein the isolation regions are thicker than the first word line insulating layers beneath the first word line electrodes. 